For some reason, all of the postive press about this game at E3 made me feel excited about this game. The demo that was released a few weeks ago confimed the purchase for me, and the fact that it has a seperate co-op campaign also makes it a buy for me as my good friend and I really appriciate split screen co-op.
The last time I played Splinter Cell was when I was about 12 years old, it was the demo and it scared the shit out of me when I set the alarm off. 
 
So I was just curious if there is anyone else like me who, hasn't really played Splinter Cell before, but is planning on buying Conviction?

I'm not myself, but I have two separate friends who are. When I asked why they just said they thought it looked different and made them excited. I wasn't aware there was a demo so I think I will recommend it to them.

It's hanging out at my school's Residence Service's Office right now.  Unfortunately they don't process packages for pick-up until after noon, so I just get to sit here twiddling my thumbs idly until then.  I enjoyed what little (very, very little) I played of the very first Splinter Cell, though I didn't get very far do to my general lack of affection for the original Xbox controller.  This will be the first game in the series I've played since then, so I hope I can have fun with it.

I'm totally in the same boat.  Never tried a splinter cell and will probably buy Conviction somewhere down the road.