Well, the free demo is cool with 25% of the creature parts to play with. If you want you can go buy the retail version which gives you access to 100% of the parts.
The full retail game comes with the full creature creator, obviously. This is just early access and junk.
With that said, I think $10 is a bit too much for this pre-release creature creator. Once the game itself comes out you will have zero use for it anymore, and the game comes out less than 3 months after the creator. You know, $5 I probably would have grabbed it. Or even if the thing came with a coupon for $5-10 off the full game then it would be fine. Or fuck, just make it a pre-order bonus. Charging for it separately seems wrong.