Treyarch is the redheaded stepchild in Activisions Call of Duty lineup. I know that Infinity Ward is no longer loved by PC enthusiasts (they sold out to the consoles, kinda...) but I have yet to play an Infinity Ward game that wasn't just balls to the wall awesome in both graphics and gameplay (MW2's single player storyline didn't make sense, but it still had great levels taken individually). Can't say the same for Treyarch, didn't bother with COD3 but World at War was meh at best. MW2's graphics are also light years ahead of the washed out grey mess of low res textures that is BLOPS.
With all of that said, Treyarch has surprised me with BLOPS in the gameplay department. They clearly were listening to the complaints leveled at MW2 (OP perks/killstreaks, lack of dedicated servers). My main issue with MW2 had nothing to do with dedicated servers but instead gameplay - there were too many ridiculous class setups like Noob-tube/One Man Army/Danger Close for which there was no counter. On a map like Terminal, just quit the game already because it's going to be a bore-fest and that wasn't the only idiotic perk, there's also Commando...etc.
BLOPS has much weaker noob-tubes and a Flak Jacket perk which ends all discussion of OP explosives. Love that.
So anyway, the gameplay in BLOPS is great, it's just the hideous graphics which look like they're still using the MW1 engine. MW1's engine looked great three years ago, not so much now.