I also hated Dungeon Siege 1, so I never played DS2 either. I heard it's more or less the same game though.
So I never tried DS2 as I feared more of the same. Someone mentioned DS2 had been different so I will watch DS3 and see if maybe it will be worth a pickup.
…and those who wanted another DS1 didn't find it in DS2.
And who ever you heard that from lied in your face, because that's RADICALLY wrong.
DS2 was everything DS1 should have been. While DS1 was diablo-with-a-party, DS2 is much more like Baldur's Gate or Icewind Dale in style.
In case there's any doubt - I fully agree with JemyM about this.
Dungeon Siege 2 is a fine game - if you can stand the dated visuals. It's miles ahead of Dungeon Siege, but it's also quite a different game. Don't expect a traditional hack and slasher, more like a hybrid action RPG/serious RPG.
The only negative thing I have heard about DS2 was that the expansion (which I guess extends the story) is absolutely awful.