It depends on game really, and I don't mind graphics. UI usually just feels clunky and barely usable by modern standards, so I spend more time fighting interface than playing. It's not the case with point and click games though, Monkey Island serie ftw, I remember Amiga version of it on about 15 diskettes and every few minutes please insert disk no X.
In case of Paradox games it's just that FtG feels the same, but is much better than EU2, which is then much better than EU1, so no point playing older versions, yes, feels more like versions than much different games. The same case may be for CK and Vicky, even though I like both older games.
HoI is imho too different between incarnations and each feels like another game, and honestly I prefer HoI2 over HoI3.
