Personally, I liked the first one better. There wasn't much demand on the system. I was able to install and play it on 95, 98, NT, ME, XP, Vista and 7 without issues (never tried it on 2000). This new one barely runs on my win 7 which is a decent machine.
The general gameplay and graphics is about the same. I've already forgotten my "login" name and password (I hope it's not need to play again as I hate online playing). I've heard mixed messages on this if it is needed.
Ive been playing the first since it came out, then i played the Beta for the second one and have been playing the actual game since release. To me its just a glorified first game with a ton of extra added features which just make it run a little more fluently and makes it easier to figure out for the new players. I cant wait for the expansions!
But also as said before this, the fact the game strains the comp so much is a nuisance...