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.
Badass Decay: Haseo, after being Data Drained by Azure Flame Kite.
Broken Base: The best way to create conflict in the .hack fandom? Ask which one is better: The World R:1 or The World R:2. Watch it burn.
Arguably everything after R:2
Crowning Music of Awesome: All the time. The DVD for .hack//SIGN gives the option to turn off dialogue and leave only the music. Considering that said music was made by Yuki Kajiura, did you really expect anything less?
All the games feature great music by Chikayo Fukuda and the wailing vocalist Tomoyo Mitani performs the Tear Jerker song to close out the the first two G.U. games plus the awesome third song. She also did the vocals for Aura's theme in the first game and more. To top it off .hack//Link also features a few of Kajiura's songs.
It's the Same, so It Sucks: The R1 games got quite a bit of flak for having the exact same gameplay mechanics throughout. This problem becomes a lot more understandable if you see the quadrology as one gigantic game split into four (like the Lord of the Rings film trilogy.)
In fact, by analyzing the game data for Infection, it's possible to find almost every single equipment and regular enemy in there (some of them were modified in the later games, however). Actually, it isone game split in four, as there's probably enough room in a single game to hold everything: there's a huge dummy file on each game with the only purpose to raise the game's size to the minimum required for a PS2 game.
Presumably because of this the GU trilogy slightly changed up the game mechanics every volume by way of Haseo's job upgrades giving him new weapon choices and new awakenings.
Les Yay: Due to If It's You, It's Okay (or maybe Bi the Way?). Subaru becomes romantically attached to Tsukasa, and the fact that "he" is a girl in real life doesn't deter Subaru in the slightest. It's suggested that after college, they began living together.
The unexpected dinosaur that appears in the G.U.+ manga spawned this.
Moral Event Horizon: There are a few nasty folks in the story, but none hold a candle to G.U.'s Sakaki, who gleefully exploited Atoli's many emotional weaknesses in order to dominate her, long before AIDA gave him a chance to take over the world from within the network. Even the fact that he himself was the victim of some Magnificent Bastardry at the hands of Ovan doesn't diminish the satisfaction of seeing him cornered and (presumably) data-drained by Aura's knights, as he screams in helpless despair.
Narm: Played for laughs. After a Quest, Kuhn admits to Haseo that his girlfriend dumped him. Before that he looked like to say something seriously.
After the Quest, he and Haseo have some friend-supporting conversation when a cute girl passes by and Kuhn flirts her immidiately.
Viewer Gender Confusion: Tsukasa's actual gender is made clear in the first episode, but The Reveal often evaded those with short attention spans. North American fandom was inundated with Male!Tsukasa fanworks... until later in the series, when The Reveal was stated in script.