These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Infinite Stratos
Americans Hate Tingle: Season 2 was overwhelmingly considered to be a disgrace by most American fans. In Japan, the series sold like hotcakes and was just as popular as the first season.
Cliché Storm: Almost every cliche you'd expect in a Harem anime, you could expect to see it in here.
Crazy Awesome: Tabane Shinonono. A Ditzy Genius who has created the IS in the first place, (presumably) programmed about 2000+ ICBMs to launch towards Japan (just to give her creation a stellar debut), and (supposedly) took control of an "unmanned" IS just to let her younger sister debut as a personal IS user on her birthday. Doubles as a subtle Actor Allusion, considering that she shares her seiyuu with Nanoha. When Tabane unveiled the IS to the world, she got a lot of ridicule and criticism. So what did she do? She befriended them via mass ICBM launch.
Not only is her brain 'over-specced' but also her body as well. After she curbstomps three of Phantom Task's finest, with one of them in an IS, she tells them that only 'Chi-chan' is capable of holding her own against her.
Critical Research Failure: A minor example occurs when after Laura first fires her railgun at Charles and Ichika, a massive bullet casing◊ is ejected from the weapon and falls to the ground. In Real Life, one of the many advantages a working railgun would have over a conventional firearm is that a full cartridge (casing, primer, gunpowder, and bullet) is not necessary to launch the projectile. There should be no spent casing, or even an ejection port. But, hey, it looks cool, right?
One theory (not tested yet) to make railguns use less energy (and they use a lot) is to fire a normal chemical burning round and then accelerate that with railgun tech (or coilgun).
Honne Nohotoke, a side-character that appeared in the anime in Pikachu-esque pajamas, appears to have gained quite a following for someone with a less than a minute of screentime.
She did show up in a few scenes wearing the IS academy's prescribed uniform, but hers seem to have overly long sleeves compared to the rest.
Maya Yamada has proven to be pretty popular despite her semi-minor role for both being a shapely/cute teacher and her IS Skills.
Among the members of Ichika's harem, Charlotte seems to be the fan favorite. See Fan-Preferred Couple. On top of being a sweet girl, her ability to excel with an older IS endears her to many.
Laura is also quite popular as well, owing in large part to her close friendship with Charlotte and the fact that so much of the comedy surrounding her comes from her tendency to make everything Serious Business.
Charlotte/Ichika. Many fans argue that it would be refreshing for a harem hero to end up with a sweet, gentle and kind girl rather than yet another violent, domineering, inconsiderate, selfish and emotionally insincere tyrant (which is unfortunately EVERY other girl in the harem, at least at first) for a change.
If this poll is anything to go by, Charlotte is by far the most popular girl, at least among the English-speaking fandom, with Houki & Laura neck-and-neck for second place, and Tatenashi at a distant third.
Faux Action Guy: A male instance of this trope. Despite being the main character and receiving training from multiple tutors, Ichika manages to lose nearly every 1 on 1 fight he's in.
Chifuyu Orimura, aka Brunhilde I - the first Mondo Grosso Champion. She's just a teacher now at the Academy, and seems to be content with it, but if her history and reputation is anything to go by, you don't want be on the business end of her in an IS suit (or, as one pilot found out in Volume 8 of the light novel, even without one). The first time she showed up in an IS, presumably at age 14, she DID break the entire world's balance of power. Now she is 24 with a lot more experience... She herself seemed to lampshaded this in Volume 8 too, when gazing at her frozen IS.
Chifuyu: When you wake up, it'll definitely be the decisive battle...
There's also Laura's Schwarzer Regen — in one-on-one combat, it's pretty much unbeatable. It has a massive rail gun as its main armament, it has an energy blade on each wrist, and it has remote-controlled tethers much like the Slash Harkens from Code Geass to restrain opponents so she can shoot them more easily. To top it all off, she has an impenetrable barrier that can block anything as long as there's only one attacker.
And then there's Tatenashi's Mysterious Lady, which does away with standard kinetic weapons and lasers of the existing IS units in favor of nanotech-weaponized water. If one wants a sizable comparison with this IS to any Humongous Mecha ever introduced in Anime, just these two words: MoonlightButterfly.
In the second season's final episode, Madoka's Kurokishi and Squall's Golden Dawn are downright unstoppable. It took a literal Deus ex Machina to deal any damage to them, and even then it was merely a minor setback.
Ichika and Charles seem close, and a lot of the Academy girls love it. No one minds however after Charlotte's gender reveal.
Laura for Orimura-sensei. Her teammates back in Germany really thought she was gay for Chifuyu.
This gets toned down a lot after her Superpower Meltdown, though, when Chifuyu tells Laura to become her own person and stop trying to imitate her.
Rin gives Cecilia a lower-body massage, complete with much laughter and squealing from the latter. (Actually, she's trying to "save" Ichika from having to do the same.)
Season 2, Episode 1. Charlotte/Laura so very much.
So much, that the other people in the store with them start taking photos.
Episode 8 of the second season has Tatenashi suddenly sneaking up on Houki while she's practicing kendo and feeling up her boobs. Later on when doing a scan of Houki to check their compatibility as tag-team partners, she's rather interested in the fact that Houki has bigger breasts than her, much to Houki's consternation.
There is a scene in Volume 4 of the novels between Squall & Autumn that is full of subtext between them which was not present in the anime.
It Was His Sled: How many places actually still spoiler-mark Charles/Charlotte's true gender and name?
Houki and Tanabe have this vibe at times, mainly due to Houki getting much of the attention from the author and in-universe getting a very high end IS made by her sister. Tanabe (for those who don't think she's crazy awesome) for being genius IS maker, able to get away with various major stunts (launching various ICB Ms), being down right unpleasent to those outside of her limited interest, etc. It's been implied that the girls-only limitation of IS is solely due to her whims.
True enough, one chapter of the Sugar & Honey spin-off is actually an excuse for this trope.
The Scrappy: Who do the haters despise the most in this show? Ichika, that's who. It's common to hear people saying that the show would be better if this bland blockhead wasn't around and simply focused on the girls doing funny antics.
Houki for being a terrible tsundere, and so-so pilot that seems to get special treatment.
Tatenashi may count due to her late entry and sueish antics, but some just ignore her existence.
Second Season Downfall: There are quite a few who feel the second season is far inferior to the first. Part of it is probably because a good 90% of the second season has been focused on wacky harem antics, with very little time devoted to advancing a plot or even having awesome mech battles (which was, you know, the one thing that distinguished this series from other harem shows). While it's true the first season had a pretty weak main plot too, it at least managed to strike a pretty even balance between harem hijinks and IS action, which cannot be said for the second season. Basically, the second season doesn't have enough Stuff Blowing Up.
There is also the issue with season 2 cramming 3 volumes into 5 episodes. Normally this alone is enough material for an entire season * Not an exaggeration: the entire first season consisted of Volumes 1-3.. The result is the elimination of anything not harem antics related, which means that Character Development, such as Cecilia's, was completely eliminated. Overall we are missing some 80% to 90% of the plot of volume 4 to 6.
Volumes 4 & 5 were actually adapted pretty accurately, as was Volume 7 (though half of V4 was covered in an OVA, and the school festival in V5 was shortened in the anime but at the same time the Cinderella play was extended). It was Volumes 6 & 8 that really suffered Adaptation Decay; those volumes are the ones missing almost all their scenes. The series started off very faithful to the novels but around the middle of the second season, the anime started taking liberties with the source material until the final three episodes went into all-out anime original territory. This topic explains all the differences between the novels & anime (be warned for spoilers that span the entire series, both books & show).
The announced "World Purge" OVA means Volume 8 may get a proper adaptation soon.
So Okay, It's Average: YMMV of course, but the show really doesn't break any ground with the Harem tropes.
If Amazon reviews are any indication, the Japanese audience feels the same way: most of the novels fall squarely in the 2 - 2.5 star range.
Spotlight-Stealing Squad: This is what many fans (particularly those of Charlotte and Laura) feel of Houki. What makes this so notable? Houki is the female lead, and the one with the closest relationship to Ichika amongst the harem. This goes hand in hand with Die for Our Ship and Ship-to-Ship Combat.
Stop Helping Me!: When Houki, Rin, and Cecilia all try to explain to Ichika how to use the IS with their Techno Babble, it only serves to confuse him. On the other hand, Charles offers to duel Ichika, and after soundly stomping him, he offers some tips on Ichika's weaknesses and explains things that makes it easy for him to understand. He also helps train Ichika on using a rifle, and seems a bit too friendly, causing the girls to get quite jealous.