I played the demo and I don't think so. It is dubbed a one hour playable demo which can be beaten in 3 minutes easily. The classic case of a lack of VRAM. Sure the environments are pretty, but by the same token are rather small and cramped, and to give the game the graphics and A.I. it needs the developer will need to keep it relatively short. Just like Onimusha, ZOE, Red Faction, as well as other less impressive games, MGS2 will fall victim to the "This game is too short Syndrome". I hate games that you can beat it one sitting, and due to the PS2's lack of VRAM most of the games are just that. Sure with the proper amount of developement time a game on PS2 can be somewhat lengthy, however most publishers want to get games on the retail shelves as soon as possible, and MGS2 is not exception. So MGS2 will have small cramped levels, so it will be shorter than what most would like (Konami even said so at E3), so the A.I. may not be up to the standards originally set. Does this make it any less of a game?
The answer is yes. Oh well at least we have Xbox and GC, two consoles with plenty of VRAM for longer, better playing, more immersive, less cramped games which have shorter developement times, and cost less to develop for.