I immediately warmed to the EyeToy after viewing the superb opening instructions (US version here). If only all games explained themselves so clearly. Instantly I was reminded of Myron Kreuger's VideoPlace (of which the EyeToy owes a huge debt) which I'd always wanted to experience since seeing in 1990 on TV.
I fell in love with EyeToy when I discovered the "Play Room" area. A choice of ten or so different multi-sensorial no-pressure activities. From popping bubbles, chasing fish, a copy-cat feature (my favourite) to crazy psychedelics. This is something that anyone who can move, can interact with. You don't even need to move a lot. Just move the camera to focus in on the part of the body of choice.
Brilliant and highly recommended to Playstation 2 users (not sure about PS3 - still haven't got one).