First off, don't watch this thing expecting it to be anywhere near as funny as Scary Movie. It's PG rated, not R, so get it through ya thick skulls that it's a family movie and is not going to have adult only humor.
Little Big Man is about a small guy who is released from prison and the first thing he does is steals a diamond with someone and some things go wrong and the diamond ends up being placed into an innocent womans hand bag. Then to get the diamond back they decide to not just mug her for it, but the little guy has a shave and pretends to be an abandoned baby left on there door step. But the little guys plans to just be in and out with the diamond go wrong and he ends up staying longer then he expected pretending to be a baby.
I kind of liked the idea of it, a midget pretending to be a baby and getting up to things that only a plot like that could deliver. There are some decent gags in the film, but there are also those that didn't work and those that could've been done much better... quite frankly i'd enjoy a nurse on Alex Borsteins knee, but they played it out like she was hideous which I thought didn't work at all. Plus, the fart/poop jokes couldve been done allot better, but there are still some decent gags in the film.
I wouldn't say it's ever going to be a classic comedy, but neither was White Chicks but you can still sit from start to finish and watch it without being bored, unless you're just expecting something huge to happen, but as I said, don't expect huge laughs like they have previously made.
My 6 year old niece watched it with me and laughed at different things to me, she loved it, and wants to watch it again, so it has replay value to some.
Overall: don't go in expecting it to be something huge, its not, its more a family comedy and the only thing I didn't like was the end of it.