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: Identity Crisis
Asspull: Deathstroke's victory over a Justice League of America team can only be described as a complete and total Ass Pull. Sure, the team of heroes he fought didn't include Batman, Superman, or Wonder Woman (two of whom would barely notice Deathstroke if he attacked them, and the third, Batman, would be ready for him if he did), but it did include the Flash and Green Lantern, neither of whom was portrayed as actually knowing how their own frigging powers worked during the fight. Key pieces are being somehow faster than the prototypical Super Speed superhero and overpowering Green Lantern's ring by developing stronger willpower (a facet that would be a reason for him to have the ring to begin with, not to mention not being how the ring works at all). It also included a direct reversal in how the Atom's powers normally work (the Atom does normally retain full mass when he shrinks) for no reason that was ever stated, and a complete and arbitrary nerfing of Black Canary's superpowers (she's easily able to rip through several feet of steel-reinforced concrete with her Canary Cry, but apparently penetrating a single layer of burlap over her mouth is beyond her abilities if its Deathstroke's burlap sack). So it was, in fact, embarrassing. For the writer.
Author's Saving Throw: Dr. Light used to be a serious threat capable of taking on the Justice League, but somewhere along the line became a comical punching bag of the Teen Titans. This mini explains why that change took place and restores him to his original characterization.
Broken Base: The Deathstroke vs. Justice League fight. For all that is holy, never bring it up in any Versus Discussion, less you want the thread to be completely derailed.
Notably, the book occupies many extremes simultaneously. Jean Loring claims not to have wanted Sue's death, but brought along a flamethrower anyway, perhaps as a baby shower present. On the other hand, Dr. Light's return to form, the upgrade to Calculator, and the rarity of a Crisis Crossover focused more on a personal level than on an apocalypse, were all critically lauded elements.
Memetic Mutation: The series inspired a fad on the Something Awful forums of user avatars showing their Wild Mass Guesses about the identity of Sue Dibny's murderer. The response to the series played a role in the formation of the "Batman's Shameful Secret" forum for comic book discussion on the site.
Shocking Swerve: Jean Loring being the murderer when pretty much all of the evidence beforehand suggested somebody else. Rather impossible in some degrees, since there is a panel where someone else's hands tie the knot on which she fakes her own hanging, which is dropped when the murderer is revealed.
Villain Sue: Many felt Deathstroke was this during the series, in which he solos the Justice League, including displaying faster reflexes than Wally West and out-willpower a Green Lantern Ring, the former being extremely improbable (on account of the Speed Force and speed being the Flash's thing, and the latter being outright impossible.
To be fair, he wasn't faster than the Flash. He just put his sword and Flash ran into it on a preset attack. It's more a case of Flash having target fixation.
The Woobie: Several, particularly Elongated Man and Robin.