I'm testdriving some games on an older linux pc, lately. And I actually have the opposite. I start them thinking "oh, crap, this is going to be soooooo bad..."
...and then they turn out to be still equally awesome as they were (except compared to today's visuals and sounds).
Still...some mentions:
-mystic quest (game boy): it had some moody music, but when replaying it, it just felt awful.
-starcraft 1: obviously, this game is by all rights and measurements a classic...but when I tried it the other day, my first thought was "okay...now how do I change the resolution so I can see more that just my own character?". Turns out there is no way to change it, and playing it on a monitor that is nearing twice the screen size than my old CRT just makes it extra awkward.
-Duke Nukem 3D: yeah, I finished it again and loved it...but keyboard and mice weren't exactly standard controls back then. There's this unresponsive, blocky movement to it. Perhaps because it wasn't 3D rendered, but still...