the game is AWESOME. Remember, there are many things that make a game great, and length is definitely not at the top of the list. It frankly, is one of the best games ever created for a variety of reasons. It's not the longest game in the world, but its definitely not "short" as some people are keen on saying. It is rather lengthy, if you try to fully complete the game (all 120 stars) and some of those stars are F^#ing HARD to get, so it is definitely a complete and fulfilling experience.
In short, GET and KEEP this game. If you know anything about videogames, you'll understand how great this game is.