Picked mine up from EB Games yesterday. I had to go to one a bit out of the way, but I checked in Best Buy and they also had some copies.
Didn't have the special edition, but I wasn't going to sneer at a $10 version of the game. Plus, they have a pretty handy way of dealing with the number of CD-ROMs they have to give you.
First impression, Onslaught has some especially large maps to work with. Of the ones I played, they had some nice flat territories, some with a much greater degree of Z-axis action than Torlan, and some that were just so large that a vehicle is the only reasonable way to get to the next node. It was just too far to run (or hop jump). I would expect that it will be considered very bad form not to provide a ride on a Manta given these maps.
Overall, seems to be very polished. Very close to the demo, although I noticed that the maps loaded slower in the full version (even Torlan).
(oh..my CD key was under disk one in the cardboard sleeve...no problems there)
lets just say that the maps are sweet. I played Onslaught in the artic territory one. The verticle rises and snow, etc made it freaking amazing and added a lot of challenge. This is 1000 times better than the demo. I am taking a quick break for lunch and going right back.