This doesn't connect much to the first game. Don't bother with Dungeon Siege, just play this game.
It still gets tedious at times. It's also a lot harder if you ask me. There are some fights at the end that feel pretty unfair. There were too many frustrating moments, but challenge isn't a bad thing. The payoff was good. The character system and better plot made you feel like you were working towards something much better than the first game did.
This doesn't connect much to the first game. Don't bother with Dungeon Siege, just play this game.