I'm kinda supprised that everyone tells that X-Com 1 is better than X-Com 2. You just compare everything in XC2 with your beloved XC1. Well I'll say that I've started from TFTD (6-7 years ago) and just week ago jumped on XC1. Well XC1 is just... smaller - everything in TFTD is bigger than in UD, from maps to ufopedia
The one thing I like more in UD is music on geoscape (but I'll say that music in TFTD is more... climatic)
That's all, never played UFO? Start with TFTD and don't hear those "fanatics" ;]