Just got back from seeing it myself. It was a definitely a crowd-pleaser, the audience I saw it with was laughing out loud at all the fun and nonsense. Groot was the highlight for me, especially his 'role' in the prison break. Not enough movies make such good use of background humour. Less good was Ronan, who was just another boring take-over-the-universe Marvel movie villain like Christopher Eccleston in the last Thor. Maybe it's because Marvel doesn't have as much to work with as DC when it comes to good comic villains, but it's a crapshoot with these movies as to whether we get bland (Ronin, Christopher Eccleston, Whiplash), or fantastic (umm...just Loki and the Mandarin, really).
Apart from that, my only real problem with the movie was the inconsistent tone. All the reviews I'd read and watched (Bob's included) before seeing it led me to believe it would just be all light-hearted and silly, like the Avengers. But it starts with the most bizarrely dour and depressing opening that would make the origin of Batman look not that bad. But then it transitions to the present day, with Quill dancing around on an alien planet kicking CGI lizards and saying "Starlord, man" like in the trailer. It was jarring as hell.
Also, I'm trying not to spoil, but there are an awful lot of fake-out death moments where it looks like one of our heroes might die, and the movie would always grind to a halt when it happens. But I never bought that they were in any danger for a second, and sure enough it would just get brushed off with a quip and we'd go back to the rollicking space comedy adventure. There's nothing wrong with rollicking space adventure, and there's nothing wrong with injecting a bit of drama, but the movie is almost self-conscious about it. It can't have a serious scene without undermining it with a gag, and the gags are what we're all watching it for.
Also, is it weird that when there's the 'reveal' of John C. Reily's family at the end, I was expecting he'd be gay? I don't know why, during the build-up I thought the surprise would be that he has a husband. That's what they'd do on Doctor Who.