If the alternative is GFWL, then hell yea to steam works, else I don't really care. BUT! steamworks will keep my saves on the cloud and have easy access to coop and multiplayer with my friends. I really loved the whole add friends to game thing when i played supreme commander 2. REAAALLY convenient and better than the way GFWL did it.
Also if you are going to buy it on steam it's going to be atleast 20-24 gigs of download