One of my problems with the movie was that is too blue for me and I usually have a darker/ more sardonic sense of humour. Many of the jokes fell flat for me and I didn't find the characters particularly interesting (though realistic). I was generally bored throughout the movie though I make an exception with the Buscemi cameo. The biggest issue many people had with this movie was (like many Adam Sandler movies lately) felt like he was getting paid to have fun with his friends which I don't take too much issue with, he had good chemistry with the other actors and I could believe they were friends. Overall; I don't hate it but it wasn't my kind of movie.
When I first saw it, it really made me laugh. Every time I've seen it it's made me laugh actually. The humor has a lot of variety, and while at times it may go a little blue, it still has a pervasive wit to the jokes that 100 better reviewed movies don't. But more than that, the characters feel like people you'd meet in the real world, and moreover, remind you of people you actually know. Every one of the characters have quite a few personality quirks, and while they certainly aren't portraid subtly, they definitely make every character even more believable. The best choice I think they made was basing the lion's share of the humor in dialogue. Not only is the dialogue funny, because there are plenty of movies with funny dialogue, it's true to life to an extent you could scarcely find a few examples of in film. That's just my opinion though and I realize everyone's tastes are different so I look forward to hearing your reasons for liking or disliking Grown Ups.