I don't think it will be success Disney hope it will be.
All things to All People: phase 2 has been very poor so far mainly due a disney/marvel attempting to make do a family friendly, funny, action packed films. both Ironman 3 and thor 2 tried to do all these things and not succeeding at all of them. this results in poor character development and plot holes. While Ironman 3 was as bad as batman & Robin, the audience and critics all over a looked the failures because Robert Downey Jr's charm. Thor 2 didn't have that luxury and was less successful. indeed the director of thor 2 did complain about this aspect.
franchise fatigue: there is also a sense of franchise fatigue beginning to kick in with the super hero genre. I know a lot of people walked out of thor 2 saying "I Just wished they had made an Avengers 2 instead of more ironman and thor films". We are going to have a lot big superhero films this year and GOG Is the last one to come out.
a flawed execution: This is almost certain to happen, Team's don't translate to film because there are often to many characters and contracts demand certain characters get more screen time then others. Avengers avoided this by having the main character history already explained. (see x-men franchise for a great example of the flaws of team film).
The Easter eggs: marvel films have lot of easter eggs, this has encouraged audience to watch them just for the easters eggs which lead up to avengers. I wonder if audiences will look at GOG and think it has little to do with Avengers 2 and thus give it a miss.
Rocket Raccoon: its clear the marvel and most of the comic book fan base are excited about the concept of talking raccoon. However, not all comic book elements transfer over so well to big screen, there is no shortage of wise cracking talking animals films out there (especially those made by Disney) I Wonder if this will actually work against it.
Disney & SCFI: Disney made John Carter of Mars the biggest SCFI flop ever made... then upon that failure ordered Marvel to make GOG and purchased the star wars franchise. its clear that Disney are making this because they want to have a good portfolio in the SCFI genre but their track record is sketchy.
Personally I think it will be alight, nothing special, but it won't be as successful as Avengers and Iron man 3 (although ironman merely piggied back on the avengers success). I know it be full of unfunny forced awkward humour but the CGI and actions scenes will be great.
would these be the people that think the avengers are Ironman's non armored side kicks and Tony stark is arrogant, egoistical, jerk, rebel super hero that is happily in love with his secretary?
Can you imagine if we got a batman begins style reboot of the iron man franchise! Tony Stark an alcoholic, manic depressive! who didn;t have a conventional damsel in distress because Pepper Potts would be married to Happy hogan! the pop corn munching audiences would loose their minds
I await the next marvel ham fisted rewriting of Ultron origins in the comics!
@kamionero: each event shaves from some of the readership and makes it more inaccessible to new readers. there is also little things like shifting house styles which make the book stand out less on the shelves. Frankly Im Surprised its gone on this long, i get the impression marvel is trying to get rid of but at the same time extract as much money out its remaining readership.