Well, it wasn't perfect of course, but I'm struggling to think of anything I really disliked about the movie. More often than not, something glaring sticks out to me immediately, be it the horrible fight sequences from Man of Steel or the continuity errors of The Dark Knight Rises. Outside of some hilariously impossible scenarios, there was nothing overwhelmingly poor to be had here. I really appreciate that Whedon didn't attempt to top the original, since to be fair, that movie will always stand out for being the first time these characters all got together on the big screen.
This one did just enough to distance itself from that, had a top notch villain, the human element that I love and a ton of lol humour. That may actually be my favourite part, as I've long since grown tired of the super serious comic book movie. I'll need to see it again before I rank it, but I'd say it was a solid 8.5/10 (I believe I rated the original a 9) and can realistically say that I only enjoyed the first one and Winter Soldier more. Good stuff all around.