Well, me and my brother have just bought spore, and i must say, it's really original!
I think the best thing about spore is not the whole RTS and the "RPG" element of the game, but more the creative side of the player that is important.
At first i was making tanks, as tanks should be, planes as planes should be, dragons as dragons should be! and so on, and on. :P
but when I play along I realised that you can ajust your creature, buildings, cars, planes, etc all by yourself, the fun thing is trying to make something completly original, totally different from your normal expectations of things.
The cell stage is quite boring though, but when you first set foot on land, it began to interest me, i've changed my character a dozen times! The concept is quite easy. It's not a game for the hard-core gamer who doesn't like to be creative.
I say buy!