I played at least 10 matches against the computer (online play was broken when I tried.. noone could join a server, connection would timeout).
My honest review is that this game seems lacking... it's kinda neat to mix/match animals, but other than that it's kinda boring
I see this game getting some pretty negative reviews (except from MS fanboys of course) and even though there are MANY possibilites for creatures, I think you will see a dominant crop show up real quick.