I played it for the first time using Deus Ex: Revision. It's very good.
Revision sucked as it had crappy textures on Hong Kong. GMDX it's far ahead, less tacky/broken and with hugely enhanced areas. As early as at Hell's Kitchen you are looking a much more realistic area (city planning, buildings, park benches/objects and whatnot) than before.
I would suggest anyone playing it for the first time to give the original with only basic engine fixes (e.g. Deus EXE) a go before playing some random modders take on what the game should be like.