It's all about Phase 1 and 5, everything in between is a mixture of déjà-vue from many other games, only that your character/creature is "yours" because you created it. The creature editor is what "makes the game" even more so than Phase 5 itself. And the problem with Phase 5 is that it gets very repetitive, and it felt pointless to just conquer so many planets that basically have no backgrounds and so on, there's too much for nothing, in other words. And Spore isn't the only one like that, for sure, but that's the point, it doesn't differ much from other similarly boring games to me.
I liked it to some extent at first, but I just asked to myself if I would really want to deal with that repetitiveness. Then I realized that I got enough of games like that already on my desk taking up the dust, and that Spore wouldn't end up there. So after three days and around 15 hours of play time I decided I'd return it for a refund, pretending it doesn't work, the store doesn't have time to check and they accepted, good riddance, I don't even care about what happens to my copy next, they could melt it into a microwave or just re-pack it and sell it as if it was brand new, I couldn't care less, I got my money back.