I have to be honest and say that I have at no point really been a big fan of this franchise. I usually love animated films, but I just never got in to these. The first one was a decent watch. The second one was a straight to video movie that was thrown on screens at a point when no other movies, especially family films were out there and it made a boatload of money. The third one was okay. And as for this one - it's more of the same. There are some good laughs, but I never felt like they've hooked me with the characters enough to care. I pretty much just watch it for the sake of saying that I did.
I would recommend that anyone who saw the others and liked them check this out. You will definitely still like this one because it really is just more of the same stuff with some new characters thrown in.