Cell Stage: Good fun but gets tedious after a while. The fact that you never get to be the biggest cell on the stage is irritating.
Creature Stage: Possibly my favourite, the inability to attack allies is annoying.
Tribal Stage: Rubbish, a piss poor strategy game. Only good thing is that some of the decisions you made in the previous stage have an effect which is cool.
Civ Stage: Not bad at all, the ideas they use expanded on would make a very interesting strategy game. Designing your own vehicles and buildings is rubbish though as it has very little effect on functionality.
Space Stage: I like this stage, though having to constantly run back and defend your planets is annoying (you're only one ship dammit! Surely your great civilization can build a couple of others to help out).
Most annoying things are the lack of connection between the stages and the lack of effect your decisions have on the functionality of your creatures/vehicles.
In Spore 2 I would like to see them make the program 'smarter' and realise that a blade attatched to an arm is going to be more damaging than a blade attached to the creatures arse. I would also like to see some of your decisions have more of an effect on later stages.
Overall, 9.0/10.0 very solid game and extremely addictive.