Titan Quest gets better as you play it more. It is set up where you go through the game quests and main story line 3 (yes, 3) times. This is similar to Dungeon Siege II. You start of on Normal mode, and you must play through 3 countries...Greece, Egypt, and the Orient. There are different monsters and a bit of a different feel to each land.
Normal mode is actually quite easy, and you might lose interest in the game at this point. But, it gets much more challenging and interesting once you start Epic - same for Legendary. At the higher levels, there are many monsters who can one-shot kill you if you're not careful.
The graphics are good, but I found the overhead cam view annoying for the first couple of hours...then you get used to it. Lots of choices for combat - melee, spells, etc - and you can combine 2 different classes for a myriad of defensive and offensive skills.
And yes...this game is very much Diablo 2 re-dressed with better graphics and some different monsters! It is a hoot when you get to higher levels and you can wander around killing the monsters - the special effects/physics are pretty good, as they go flying in the air...see the screeshot below taken during a raid on a Tiger mob...