Yes, but that's because Microsoft is paying the bills. Problem with downloadable content is that the development of it costs money, and it doesn't increase sales, so it doesn't bring any money back in. The reason UC has some is because the stuff was taken out of the final build of UC so that it could be released later on. You should already have those levels.
MechAssault is like the dream on any online gamer. New maps, modes, and characters. Problem is, you'll only see that from Microsoft.
Premium content will likely be coming shortly.
And don't forget the Splinter Cell level coming. I guess I should go back and beat level 2
It's been a while since I have played
