Planet 51 isn't as good as Monsters, Inc- not even close...its ok...but not epic-great, Monsters, Inc has alot of well placed and well used plots which really fires the audience's imagination by contrast Planet 51, has a lot of re-cycled Hollywood 'standardsised ideas' from previous films of the past 30 years, it was very clever at that, it somewhat for the older audience (us) to play 'spot the famous cues', 'ah that was in Alien, or that was in Back to the Future', etc etc. Its displays of motiffs, montages, or virtual props were barely original....in so saying this, its a clever film, alot of effort to put it all together but it just didnt have the magic or emotional power of "Monsters, Inc"