Ars Technica's Playstation 3 review really nails it:
I think my main problem with the PS3 is that philosophically, it's a confused system. It doesn't really know what it wants to do. The 360 wants to be a social system; it wants to get you online, talking to people, playing these fun little minigames, and going for the high score and bragging rights. It wants to bring you together and make you remember what you love about gaming.
The Wii wants to get you off the couch, for you to be physical and to be part of this game world. Wii wants you to connect and to get your friends and family involved even if they don't like games. The Xbox 360 and Wii are systems that know what they want to do.
The PS3 doesn't have any grand ideas; Sony wanted something high-tech, so they started from scratch with the processor and GPU, but what does it get them? Very little so far. The controller is a mash-up of ideas from their old systems, the 360's triggers, and the Wii's motion-sensing capabilities, but once it has that tech it doesn't really know what to do with it. The Blu-ray adds cost, but adds very little to the gaming experience for the user. It's great as a media player, but for those of us who love games first and foremost, we have to look at it skeptically. The PS3 is a system with no core message, and that is what keeps it from being elegant. Will it do great things in the future? I hope so, the possibility and potential are certainly there. For now, it's power looking for a mission statement.
Read the full review for why. As for me, I really want to try out the Wii with the Wii-mote. Any place in Singapore that has one on display?