It's brief and feels like every FPS I've ever played before, just prettier (and even that is probably debatable, as PC graphics overtake console graphics again... FEAR2 looks amazing on my machine).
It went from a must own to a must rent, despite the fact that I've preordered it.
I didn't realize there's no coop, so it's just another COD4-type game with a 10 hour single player and a level based online multiplayer. Most of my online is coop with my friends, and not enough of them have PS3s. This has been in production for so long, until now I guess I assumed it would have had coop (but maybe it's been worked on so long that trend hadn't taken hold yet) and a longer campaign.
There's no gimmicks in the demo to really hook you other than graphics.
You can easily download the demo. Sign in under your normal account. Go over to user, and create a new one. It asks what region, select UK, and nothing else matters (may need a real zip code, can use 10001, and you dont need a CC to create your UK PSN account). It took me as long as it takes to type bogus address info to create the account and boom I was downloading. Very quick/easy.
Downloading The Show demo now... 30% in, it's taken 7 minutes, im wired.
Edit 22 minutes in... 80%.