While the first diablo is a very good game, diablo 2 is a lot better. When you add the latest patch you get so much more content into the game. If you like collecting loot you'll love diablo 2 <img src="/ubbthreads/images/graemlins/biggrin.gif" alt="" /> There are tons of set items, unique items, and then runes which you can place in socketed items in the right order to create runewords.
Diablo 2 is basically like the first, but with so much more stuff and somewhat better graphics. The only thing you don't see enough are skill points.