Just yesterday i mentioned the whole point of this topic on another one (can't remember wich one) and mentioned that old classics trample the new games when it comes to having fun.
Games like doom and hexen, both incredible for its time, may not hold up anymore, but games like Deus-ex and System Shock 2, the old rpgs and jrpgs like Classic Final Fantasies, The first 2 Suikodens (wich i'm replaying right now), the Baldur's Gate series and old creative fighting games like Bushido Blade I & II... All those games, despite not looking as good as the new ones, are way better designed and way more fun than their newer cousins.
For example:Mass Effect promissed a deep and rewarding exploration of the game's world and an engaging story, instead we get a few story related planets wich we can't really explore and a bunch of planets in wich the exploration feels more like a driving minigame that gets old quickly. The story wasn't bad, but tripped on a lot cliches that any old school gamer who hasn't lost his ability to follow video-game logic could easily identify to know what was going to happen ahead of time. Baldur's Gate on the other hand, had beatiful sceneries full of unique sidequests that would give players that nice acomplishment feeling whenever they stumbled upon it, that would give the players a reason to explore, to hit every tavern and house on the place to find people to help or to rip off. It was a deep and rewarding game, with an incredible story to back it up.
Games nowadays just feel rushed -both story and gameplaywise- in comparison to the deep and genuinely fun games of old. Bioshock for instance is a good and beautiful game, but it can't hold a candle to FPSRPG classics like Deus-ex and System Shock 2 on any category other than textures.
EDIT: Just so i won't completely derail from the topic, some games are indeed crap when you don't have the pink-googles on. I used to have great memories of WWC Royal Rumble for the SNES and so did a friend of mine, so decided to pick it up for nostalgia's sake. We played for about 5 minutes before realising how crappy it was and moving on to Toejam&Earl for the Genesis (wich is still hilariously fun, even after all these years.)