I simply don't understand why it surprises people that this was unoriginal. The first film was fairly cheap and made BANK and the reality is the vast majority of casual movie goers (at least those who this is directed towards) are not looking for a complete change. They wanted this. They didn't want the film and the characters to be tampered with. Well they got it, and from what I've seen leaving the theater and talking to friends who are not necessarily critics, or even avid film fans, they are happy with what they got. There was simply no reason for the film to be original. Doing what they did was safe, and I guarantee you that you'll be hearing quotes from the movie and jokes about it for another two years.
I will say that I enjoyed it. It is obviously not groundbreaking, but at the same time it was fun (although it was about as fun as rewatching the first). It clearly does nothing new and yet it is still mildly amusing. Worth the 5 bucks for the matinee showing? sure. Is it something you'll find fascinating? no.