The first game was surrounded by a huge hype when it came out based on which I bought it. The graphics was OK, the story is almost non-existent. Side quests were really boring - go to level X, kill a big bad guy. First 2/3 of the game were really easy, the last part was really hard. It became very boring for me after I descended several levels into first mine. I had to force myself to finish it.
This is coming from a guy who finished Titan Quest, Diablo 1 and 2 (all of them with all the add-ons) on the highest difficulty levels. I am not even sure why it was so boring. Lack of a story or good atmosphere? Diablo and Titan quest have both.
I might sound like a troll, but I am not looking forward for the next game. I still might give it a try if they come up with Linux version. The game will probably have hard time to compete with Diablo 3.
If it's worth doing, it's worth doing for money.