I just bought the D2R + D3 package on sale. I played D2 to no end in the past (single player, and never played D3), but I don't know much about D2R other than it gives a facelift to the game.

So what are the most significant balance changes compared to the original? Skills, uniques, affixes? Runewords? New item types even? My general assumption is that most builds that worked well in the past will still work well now.