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: Countdown To Final Crisis
Bile Fascination: A number of people have read this series and picked up the trade paperbacks because they'd heard a number of critics deride it (whether it be their peers or professionals).
Creator's Pet: Forerunner, who the creators obviously thought would be seen as really cool and a breakout character. She even got her own (half a) spinoff miniseries. Fan reaction was tepid at best, and most seemed to view her as The Scrappy. Apparently this eventually got through to the writers, as the last issue of the miniseries has Forerunner transported to a distant planet to rebuild her species.
The whole series can be this if you take the view that it's so bad it's funny. Its all unintentional, but there are some comedy gems like Jason Todd (the gun-wielding crazy guy) telling a Monitor that he's not fond of gun-wielding crazies, Donna Troy's "I'm Donna Troy BITCH!" and of course "I'LL KILL YOU TO DEATH!" from Superman-Prime. There's also Jimmy's awful Mr. Action costume and Darkseid on Mary Marvel's couch...
It Gets Better: The Earth-51 arc. It went on (almost) uninterrupted by unrelated things, had a lot of cool fights, some really strong moments (like Jason Todd meeting its Batman and this Batman's death) and ended with a bang. Sadly, right after that, the series became much worse than ever before.
They Wasted a Perfectly Good Plot: Jimmy Olsen gets all his Silver Age powers back! Brother Eye merges with Apokolips! Mary Marvel, "deserted" by Captain Marvel, turns to Black Adam! Harley Quinn and Holly Robinson vs. Granny Goodness! A crazy, universe-hopping adventure searching for a character missing for (relative to the reader) years! Paul Dini writing! A lead-up to the biggest Crisis of all! A followup to the beloved 52! A look at the seedy underbelly of the DC universe from the perspective of two repentant Flash villains! The genesis of the Kamandi-verse! What Could Possibly Go Wrong??! Short answer: EVERYTHING.
Also, Hal Jordan, who blasts off to Oa to get help with the Morticoccus virus and warn off visitors to Earth, only to carry the virus across space, breaching its one-planet quarantine.