The demo's pretty short but you get a pretty good sense of the controls and basic mechanics. If you're into the COD games and love multiplayer, i would say go get that, but Uncharted does seem pretty impressive. Good controls, tough as nails AI (or at least smart AI), beautiful scenery. There weren't really any puzzles in the demo, so I can't really give any info on that. Based on the demo, I'm definitely buying this game. I'm a little bored of straight shooters at this point; been playing too much Halo. So I'm definitely choosing this over COD4. Plus COD's singleplayer is supposedly rather short, and right now I'm looking more for a story driven deep single player game after playing so much online Halo.
My Top 5:
Shadow of the Colossus, Metal Gear Solid 3, Shenmue, Skies of Arcadia, Chrono Trigger
My 2 nex-gen systems: PS3 
and Wii 
Prediction Aug '08: We see the PSP2 released fall '09. Graphically, it's basically the same as the current system. UMD drive ditched and replaced by 4-8gb on board flash memory. Other upgrades: 2nd analog nub, touchscreen, blutooth, motion sensor. Design: Flip-style or slider. Size: Think Iphone. Cost: $199. Will be profitable on day 1.
