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.
Cliché Storm: The first episode has been called out for having a lot of this including an invasion, a high school student going to school, the apparent death of a love interest, etc. It doesn't help that viewers keep comparing with Valvrave the Liberator (See Counterpart Comparison). On the other hand, the use of time travel has made the series stand out a bit.
Counterpart Comparison: To Valvrave the Liberator. The two series feature a seemingly similar premise of an ordinary high school kid meeting and teaming up with an experienced white-haired (or in BC's case, blonde) teen soldier, with the high school kid piloting a Humongous Mecha after his potential love interest seemingly dies. That they both come from the same studio doesn't help. And considering how the other series turned out, for some of the viewers saying stuff "Please don't be Valvrave!" has become a recurring comment in BC's forum threads even before it airs. On the other hand, other hoped that it would become just as crazy.
Expy: The Weinberg siblings are very similar to Thomas and Relena Norstein from Digimon Savers.
Genius Bonus: The power output of the Gorgon Nectar cannon in the last two episodes is equivalent to 50 megatons of TNT. This is a match for the explosive power of the Tsar Bomba, the most powerful nuclear weapon ever created by mankind. With that much raw energy hitting Aoba & Hina's Coupling shield, it's no wonder it tore open a rip in the time-space continuum...
Foe Yay: It's a complicated example to say the least. In the original time loop, Aoba was left in his original time and Hina wound up with the Alliance. Bizon was her main rival on the battlefield, but in later time loops she wound up with Zogilia and he wound up developing feelings for her.
Ho Yay: The two main male leads have barely interacted but the viewers are already seeing a lot of this with the "nice coupling." Even this is followed by an actual proposal so that the two boys will connect...
Not to mention the compatibility they have when coupling. The way the characters describe it doesn't◊ help.◊
Episode 5 has this: Dio: Don't slam that into me! /Aoba: I'm doing fine, am I not? /Dio: If you want to back me up, at least be honest.
In episode six, a new Coupler shows up and Dio can't sync with him, but Aoba can, and Dio is shown to be rather upset...
The latter half of the series does away almost entirely with this, surprisingly. If one were to watch the show without dialogue involved, it would be quite easy not to see it, as much of the Ho Yay in the series comes from the "Coupling" terminology.
"Is it 2014?"Explanation While the show was slated for release on January 5th, it was actually released on January 1st, New Years Day. When the first antagonist appears, he travels back in time to the year 2014, and immidiately asks, "Is it really 2014?" This has lead to many New Years jokes.
Say: "connect with Dio."
"Darth Vader?" Explanation (big spoilers) Bizon's aged appearance and his heavy life support in the final episode's post-credits scene is reminiscent of a certain Dark Lord of the Sith, not to mention the whole Love Makes You Crazy thing going on with him.
Moral Event Horizon: In season two, Bizon/Evgeni sacrifices a huge chunk of the loyal Zogilian forces defending their Kill Sat in order to lure the Alliance members attacking it into a trap.
Narm: The first episode had a robot from the future missing every single attack on a kid running on a bike. Well, looks like all techs no brain.
Another common complaint about the series was that the series, as a whole, was Narmtastic. Some viewers argued that, if it had gone the Mazinkaizer route of insanity instead of leeching off of Gundam's stock tropes while playing the romantic angle as seriously as possible, it might have been more than So Okay, It's Average.
Narm Charm: A lot of the show's fans would argue that it has this, citing its earnestness and competence in executing typical mecha tropes.
Rewatch Bonus: The last episode reveals that the scenes scattered throughout the series colored in sepia are actually events that happened in different timelines.
They Copied It, So It Sucks: A common complaint about the series is that it's too similar to other mecha series Sunrise made, which is often a starter complaint for every Sunrise mecha series since just about all of them use the "reluctant hero thrust into war" plot device. Each series usually starts to differ after that.
They Just Didn't Care: The composition and screenplay from the opening bears strong similarities to the openings from Gundam SEED. It's worthwhile to say that anime was made by the same studio but even as a tribute it goes really far.