Couple of things;
-Campaign was decent, though that one Vietnam barrel mission is absolutely awful. As a full product it's better than MW2 or WaW's campaigns, but MW2 had far more memorable set pieces. (MW2 had No Russian, the entire US invasion, breaking into and out of the gulag, etc. Blops has... uh, breaking out of the gulag.)
-Multiplayer maps are pretty good. Launch reminds me of a larger Ambush, Havana reminds me of a smaller Crossfire. Nuketown is a decent map (far better than Rust or Shipment) but it really needs to get out of TDM and be relegated to S&D and FFA. And Team Tactical. Haven't been able to form a full opinion on them all but there's nothing glaringly terrible.
-CoD points system is pretty mediocre. Want an emblem on this gun? Spend points. Want an emblem on that gun? Spend more points. Part of CoD4-onwards' multiplayer philosophy is the whole carrot-on-a-stick approach, and in Blops you don't feel that impetus to level up and unlock stuff at all. It's just... there.
-AK74 + warlord with a grip and rapid fire is ridiculously overpowered. It's about as bad as the UMP45 if not worse. Why did Treyarch give an SMG a grip?
-Sniping is literally pointless, they went too far adding sway after you scope in. You're always better off using an assault rifle with an ACOG.
-In general the multiplayer hasn't really gripped me at all. Don't get me wrong, it's fun and not as frustrating as MW2, but it lacks the elements that keep me coming back. I dunno, we'll see if this improves.