As someone who loved the Diablo series, I think Titan Quest is one of the best hack and slashes out right now.  I've played other new ones in the genre, such as silverfall, and I think Titan Quest is great.  Here are some pros/cons:

Pros:

-Great graphics.  While this isn't a huge deal, just looking at the environments in TQ is awesome

-Amazing class/spell system.  You can play through several times just to get all the spells/character builds.

-Huge selection of enemies, and a few good boss fights.

-Long singleplayer mode

-Co-op is a LOT of fun.  I played through with a buddy and it was a lot of fun.

Cons:

-Item system sort of blows.  You'll find worthless items everywhere, even level 5 items at lev 20

Secret of evermore

Seriously PC games are sweet, but that game was amazing...gameplay, story, magic system, etc.  I would love to see a next-gen version with tons of alchemy and great graphics.