$9.99 is a great deal that I wouldn't pass up for that game, GFWL or not. As someone else posted, you're still going to have to use it regardless of whether you get it via Microsoft or Steam.
As for GFWL, I don't find it that intrusive at all, but of course, that's just my personal take on it. Everyone has their own opinions, so now you just have to decide whether it's worth the wait for Steam to sell it cheap or go for it now. My take is, go for it now since you will still have to install GFWL even if you purchase it from Steam.