Spore is more 'toy' than game.It is designed to make you think about science and the universe we live in. It is made to invoke feelings of awe and amazement not so much in the game itself but the world around us.
The core gameplay draws unashamedly from other games and as a end result is rather shallow. As a hardcore gammer I found my self experimenting with the customization only a little and rather plowing through until the games 'end'.