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.
A rift seems to have developed between fans of the most recent team led by Star-Lord and fans of the original team. Especially when the 2014 film was merely being talked about, and was set to include Star-Lord's team; which eventually turned out to be the case.
Some Spawn fans are not happy about the appearance of Angela in the current series.
Volume 2 not featuring the same team who were in the original series.
Before volume 3 had been released, some fans were not 'pleased' with Star-Lord's retro inspired redesign nor Gamora's costume changes, and let's not even start about the inclusion of Iron Man to the cast.
In volume 3, he's not as well liked as he was in volume 2, mainly because of how he gleefully shouts about murdering enemies, and because he now seems to have a disdain for Earth, both traits that had not been there before. On top of that, his origins being changed from a mutated raccoon to a member of a race of aliens that look like raccoons.
As of issues 7 and 8, both complaints about Rocket Raccoon seem to have been addressed, as Rocket referenced his original origin and other character have discouraged Rocket from using his new catchphrase as they find it "annoying and disturbing."
Rocket's origin and species seems to constantly flip-flop from issue to issue.
Bring back DnA(Dan Abnett and Andy Lanning) has pretty much become the fandom's catchphrase. Sadly Abnett and Lanning no longer work together, but did do two final Guardian's comics before their split.
There's also the involvement of James Gunn at all, after some internet bloggers uncovered his year old "50 Superheroes people want to sleep with" list, which was filled with controversial comments. Gunn has since apologized for the comments, stating that he no longer thinks such things are funny, but people are genuinely split on it either making him a horrible person who shouldn't be directing, or thinking its just some jokes that got taken out of proportion.
Even ignoring that, however, the fact that his past credits include writing for Troma and the loathed Scooby-Doo movies, as well as the mixed reception to Super (and the horrendous reception to Movie 43), lead some people to question his worthiness to be directing for Marvel. Conversely, there are plenty of people who loved Super as well as his earlier film Slither who are looking forward to the film primarily because of Gunn's involvement.
Fans of the original lineup wanted the movie to focus on them or at least feature more of them (only one member is from the original series).
The casting of Djimon Hounsou as minor villain Korath, as some fans had hoped he'd get to play Black Panther in his upcoming film. (Including Hounsou himself, who still wants to.)
There are those who love the sense of humor showcased in the trailer, whereas others are less enthusiastic.
As noted below, Brett White was quick to make a post about the audacity of this film and its characters, whilst Wonder Woman's movie debut had been continuously postponed. Not long after, Wonder Woman was announced to be making an appearance in the sequel to Man of Steel.
The comicbook version of Drax has been revisioned a few times with the most recent version (a slimmer but strong body, a dark mood, and duel daggers) leading many fans to compare him to Riddick. This movie uses this version of Drax while also starring Vin Diesel as a separate character. Made even more fiunnier when you take into account that Dave Batista starred alongside Diesel in the above mentioned film.
Spiritual Successor: To people not as well-versed in comic books, the film is drawing a lot of comparisons to Farscape, due to its lineup including a gentle character who is not to be reckoned with (Zhaan/Groot), a snarky white leader guy (Star-Lord/John Crichton), a small anthropomorphic talking thing (Rocket Raccoon/Rygel), a big, intimidating guy (Drax/D'argo), and a deadly-yet-also-sexy woman (Gamora/Aeryn). Ironically, an actual Farscape movie was announced shortly after the original teaser trailer was released.
Meanwhile, gamers are comparing it to Sly Cooper (as both Rocket and Sly are snarky, agile, anthropomorphic talking raccoons).
It's also getting a lot of comparisons to Firefly in terms of tone, character archetypes, and visual style. The fact that the creator of Firefly, Joss Whedon, is the director of both of the Avengers movies (and a large creative force in the MCU) definitely helps.