I always have a weird feeling with watching sequels of cartoons, especially after they passed number #2. In this certain case, i wasn't really fun of the third movie so i can't say i was all too hyped to watch the fourth one. But how can you say no to Scrat and Sid?:p
The movie starts with Scrap creating the parting of the world. And then chaos happened.
There are many new characters in the movie, like Manny's daughter and Sid's grandma. I found Manny's daughter a little boring and annoying since her storyline was the usual "wanna hang out with the hot guy, having fight with bff, realizing i was wrong" teen thing. On the other hand, Sid's grandma was awesome. She totally stole his thunder and she was one of the funniest characters in the whole movie (along with the seal pirate).
In general is an average movie but at least it was better than the 3rd part. I liked that the trio was once again alone working their problems. It's easy to see Diego's development as a character. He stands out on that aspect. There are jokes and funny scenes all around, with some really really good ones that will let you laughing even after the scene has ended. And there is even a song in this one from the pirates (and one at the credits). I don't really need to comment on the animation/graphics part. From the trailer you can see what you are getting.
At the end, i'm happy i picked it up. It was interesting enough to keep me in and i had my fun watching it. Not only that, but i can easily rewatch it once or twice more.