I'm still impressed with what Valve managed to do with Half Life 2, and it's Steam implementation. Sure there was a demo, and sure it sucked a lot of people in, but that was then...
The best and most important thing that I think came of it (from a hindsight point of view) is the stat tracking that Steam allowed. It provided bulk, raw data on system types, player profiles and time spent in-game. But not only that, it also went deeper. It tracked how much time was spent on levels, and if and where people played to.
There was one level in particular that people really struggled with. Spent more time on that one level than any other - and it proved to be a game breaker for some. So Valve noticed that that one level was causing all sorts of problems for people. Next patch comes around, and they've tweaked that one level a little. More ammo, fewer enemies - and more people finishing the game!
What we've got here is real-time stat tracking on a level never before possible. Now while this is possible via demo's - it's real benefit is in beta testing, or even post release.
So demo's? Slow decline I think. But hell, these things go through cycles. We started off with Shareware and Freeware, then demo's - now we're in the era of open beta's. What next I wonder??
