I've gotten completely hooked. My username is 'whoosp', and thanks to EA's fantastic web integration, you can see all my creations and sporecasts on the web (there's nothing quite like the first time you see a pristine new planet, and populate it with naked homer simpsons). The whole experience is really phenomenal - although a bit buggy with the sporepedia management, I'm sure it will improve over time.
If you haven't played it, and you're a fan of any sim game whatsoever, I highly recommend you try it out - don't form an opinion until you're done with Space stage, because parts of the earlier stages are a bit lame.
And of course, like any good app these days, it has a vibrant community... where you can see artists at work like this guy, who made a spaceship that looks like an iPhone (see the creation video). :-)
I just went out and bought it last night. First time I ever actually paid $50 for a game, but it has been fun. Just got to tribal stage. Will check out your creatures...