Well, as far as the DLC, I think most of us are waiting for Ceph Walka's YouTube video review. He said he's buying it today and will play it and post a review of each map and the weapons that are coming with it. It's not a day 1 buy for me because - like U said - the population is low right now.
The campaign achievements are glitchy, too. I can't complete my game because I found all the Intel items before the SP patch came out and now two of them don't register and they're not where they're supposed to be. (Or anywhere else on the map, for that matter.) So I'm stuck at like 98% complete. You'd be O.K. as long as you updated everything before doing the campaign.
Personally I don't like the C3 campaign as much as the C2 campaign. Sure, the graphics and all that are better on C3 and the predator bow is fun, but I just like Alcatraz's story line better. Don't know why.