I'm rewatching at the moment too (FUNNILY ENOUGH). I loved it as a teenager and it holds up better than I'd expected.
The main thing that dates it is a tendency to turn various flavours of effnics into cyphers for mystical spooky stuff (South East Asians = inscrutable organ harvesters, Haitians = voodoo witch doctors, Native Americans = werewolf botherers... they get quite a lot of mileage out of it actually...).
I graduated to watching all the dour post-Watergate thrillers that it cribs from, and it's edifying to see that it does alright in comparison.
First 4 series were superb but it went downhill fast after that. I don't see the point in making new shows even though the 2 original stars are in it and Chris Carter is behind the idea i think it's best left alone.