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: Sonic Unleashed
8.8: IGN and Gamespot gave Sonic Unleashed for the Xbox 360 a 4.5 and 3.5, respectively. Gamespot's score is an especially sore point, as it gave Sonic the Hedgehog (2006) a 4.0. The "inferior" Playstation 2/Wii version (by Dimps of Sonic Rush fame), however, averaged 7.1.
Angst? What Angst?: Sonic is pretty mellow about Eggman completely beating him and his nightly transformations. Maybe beating down pieces of a Cosmic Horror is a great stress reliever?
Best Boss Ever: The Egg Lancer, and that goes for both versions. It's a very challenging and elaborate boss fight with sections involving wall-running, dodging lasers, and making successful quick time events to do massive damage to the boss. It's quite telling that it's arguably far more elaborate and challenging than the final boss of Sonic Colors.
The Egg Dragoon is another contender, due to the awesome music, the epic scale, and the incredibly satisfying QTE's. Plus, Eggman gets to be the Climax Boss!
Best Level Ever: the general consensus for either version seems to be Rooftop Run Day.
Broken Base: Do yourself a favor, don't ask the online fanbase if this game is good or not. Another point of contention is Wii/PS2, with many arguments over whether the game is better than the HD version, not as good but good in its own right, or an abomination that never should have been made.
Critical Dissonance: While the HD version of the game got lower scores in average than the SD version, the fans thought the opposite.
Also, quite a bit of fans believe the whole game was good while the critics say it was bad. May or may not overlap with Critical Backlash.
Demonic Spiders: Dark Titans (incredibly powerful and can stunlock Sonic to death), Killer Bees (incredibly hard to hit and ridiculously damaging), and Fire Masters (need to be put out with a water barrel, otherwise just touching them will set you on fire).
Ear Worm: The intro to the Werehog battle theme, which will play over and over again for every scrap you get into as the Werehog. Da-da-DAH da DAH daaa da-da-DAAAAAAAHHHH DAH!
Game Breaker: At least for Werehog stages in the HD version, once the player unlocks a certain move (Dash + Jump + Straight attack), there is really no fight in the game that will give him/her any trouble. It hits harder than the average attack and has massive knockback and hitstun. To put this in perspective, it stuns Dark Titans out of any of their attacks except the jump shockwave.
The Wii/PS2 version doesn't even take as long to obtain the game-breaker, as your dash attack is all you'll really need in most fights.
Genius Bonus: Remember Popping Eggcorn sold at Eggmanland? Well, "eggcorn" is a real word. It was coined in 2003, meaning the word was only five years old before it appeared in Sonic Unleashed.
Goddamned Bats: Fittingly, the Electric Bat and Dark Bat Sniper enemies (in contrast to their Helpful Mook relative). Also, enemies like Frights and Rexes can be annoying in large numbers. Let's just say the vast majority of the mooks in this game basically fit this trope, when it comes to the werehog levels anyway.
Good Bad Bugs: Not a bug per se, but traveling salesman Wentos can be exploited for nearly infinite rings, cutting the level grinding time required to unlock special moves considerably.
He Really Can Act: Jason Griffith, after years of criticism of his Sonic voice, demonstrates the ability to actually be a fairly emotional Sonic. A pity that the game that he got his act together was also the last main platformer where he voices Sonic.
Most Annoying Sound: Sonic's "whoo"s in either version when you use the boost, although arguably more notable in the Wii/Playstation 2 version since you can't extend the boost by holding the button, and thus have to press boost more often.
Werehog. Battle. Theme. A decent piece of music in and of itself, but you will hear it so many times...
The near-constant sound effect of Chip's wings flapping during the cutscenes can be a bit grating.
Nightmare Fuel: While Dark Gaia is creepy looking in its own right his Perfect form is really horrifying, especially the transformation scene mentioned below.
Also the later part of the opening cinematic is pretty tense as well, with Eggman showing that he's not so harmless by painfully forcing Sonic out of his Super state (although the previous mentioned Memetic Mutation can makes this Nightmare Retardant for some), then using the energy to crack the planet apart releasing an Eldritch Abomination, followed by Sonic transforming into the Werehog before Eggman sends him out the airlock and he plummets to Earth.
The Nightmare enemies in general.
Nintendo Hard: The Playstation 3/Xbox 360 non-story Acts, Eggmanland, and Dark Gaia. The Day rankings can also be soul crushingly brutal.
Word of God has it that the Werehog was added, among other things, to increase the length of the game, a job it is a bit too good at (a typical Werehog level is about three times the duration of a Sonic level). There are also segments near the end of the HD versions where a typical player will probably have to go out and constantly replay the levels for Sun or Moon Medals in order to unlock the next stage. 120 Sun Medals to unlock daytime Jungle Joyride? Ouch.
This is also present in the Wii/PS2 version, where (after beating the game) players may need to grind for medals in order to unlock Gaia Gate puzzles, which will allow them to unlock extra levels.
Squick: Perfect Dark Gaia. He opens his mouth and seven freakishly huge eyes come out, as well as two pairs of arms that literally rip through the skin of his body and make a bloody mess. You eventually defeat him... by ramming said eye. Blergh.
Dragon Road Act 3 (The Wii version, at least). The level doesn't get so bad until you get to a part where you have to fight a bunch of enemies on platforms with no safe ground below you, and it can be frustrating as most attacks move you forward and closer to the edge of a platform, some of which aren't that big, and it can be easy to accidentally dash and start running too fast and right off the platform.
Jungle Joyride Day. At first, it's not so bad; a fair quick-stepping challenge with a lot of alternate paths to go through. But when you get to the water-running sections, it starts getting difficult for first-time players due to those sections' awkward sense of direction. Also, the stage is marred by more framerate issues than any part of the game, which can definitely throw you off.
That One Boss: Dark Gaia. The Chip segments are easy, but the Sonic segments require you to rush over to Dark Gaia's eye within a very short amount of time, and it's near impossible to do.
Many people who replay it later on find that it is much more fun than it was on the first run. Because of the game's difficulty (especially in later stages), it can be frustrating to play at first, but practicing the game's breakneck speed, it becomes a lot of fun to just speed through the level.