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.
When Leinil Yu was providing artwork for the series, he continued to include Iron Fist in his classic costume even though the character had debuted a brand new costume a few months earlier in The Immortal Iron Fist, and constantly featured Howard the Duck in group shots of various heroes not in the team.
Creator's Pet: Luke Cage for Brian Michael Bendis, whose run on the book saw him go from Hero For Hire to leader of the New Avengers, and is one of three characters (The others beingWolverine and Spider-Man) to remain on the team for the entirety of the first two volumes. While he did become a more mainstream character under Bendis, many grew tired of his exposure over the years.
To a lesser extent, Jessica Jones, who was merely a supporting character in the first volume before becoming a full fledged member of the team following Dark Reign and actually was created by Bendis. While she was initially a very liked character, especially due to Alias, fans grew tired of her very quickly, due to her seemingly needing to be in everything.
Hilarious in Hindsight: In an early issue of the series, Daisy Johnson is needed and afterwards, she declares that her Avengers codename will be Quake. Steve then informs her that they aren't looking for new recruits. Years later, during Hickman's Avengers, Tony and Steve are expanding the lineup, and right there on a list of recruits is Daisy Johnson.
Ho Yay: When the embarrassing truth came out that Jessica Jones had a crush on Peter Parker when they were in high school came out, Spider-Man attempted to reassure Luke Cage that he had no designs on his wife. He then went on to ask if the way were clear to Iron Fist...
The Scrappy: The Sentry is universally hated by this point.
They Changed It, Now It Sucks: The reaction a number of "old school" Avengers fans had, with the initial line-up featuring only two classic Avengers and the shift away from the global level threats the classic book dealt with.
Unfortunate Implications: (WARNING: lots of spoilers for the end of the Bendis run) In volume 1, Brother Voodoo replaces Doctor Strange., Then, in volume 2, Voodoo perishes in battle with Agamotto during the first arc, after which his vengeful spirit brother kills Victoria Hand, Daimon Hellstrom, Baron Mordo, and Jennifer Kale before attacking the Avengers themselves. The final issues reveal that all these events were just a test of Strange's ability to act as the Sorcerer Supreme, and of the characters killed, only Hellstrom is said to be Not Quite Dead, and Mordo has returned elsewhere. It's hard not to read it all as a heavy use of Stuffed into the Fridge and Black Guy Dies First simply to ensure that Status Quo Is God.