Titan Quest is well made with wicked scenery and enemies but suffers from some serious gameplay flaws.
The BAD: The developers have made some really strange gameplay decisions with this game that really suck! For starters just about every battle you have (and there are thousands) there are 5-15 equipment/money drops to pick up. At least 99% of these are non-magical and useless to you so why have them? You don't need to pick them up to sell them because the monsters and chests give you stupid amounts of money anyway and you very quickly become loaded (which you dont need anyway because the 1% that gets dropped are always awesome weapons). It gets extremely tedious clicking chests after a while because instead of just clicking once to pick up the money it spreads the money out in bags which you then have to click each one individually sometimes 4-5 clicks. Bear in mind this happens every battle more or less (probably every 1 min), in the 40+ hours it takes to complete you soon get very fed up picking up stuff.
Which leads to another point. The treasure you do pick up is always better than what any vendor in the towns is selling. I did the whole of game in normal difficulty without buying one weapon/enchanment from a single vendor because I always had a better one equipped. Also because there are always loads of good weapons it means when a boss drops something decent you usually have something already better that a skeleton dropped several hours earlier.
One thing that is exciting about RPGs is saving money to buy new weapons/armour or killing the bosses and finding some awesome ring or something. This game takes away that by giving you too much.
Another main issue is how repetitive the fighting and monsters can be. Although the monsters look great and are very diverse they all fight very similar and with similar tactics. This is fine when youre on xbox and you button mash as you still have to kinda aim but it just doesnt work on the PC as all you do is click and hold the mouse. Again it becomes rather boring after a few hours play. It would have been nicer to have less monsters but make them more challenging and also take into account their class or size more. Most groups you will find it's harder to kill the magicians than the warriors and you can't help feel disappointed when you see a massive troll for the first time expecting a mammoth battle for you to kill him in a few hits.
Some bosses are like this. Some ridiculously easy some annoyingly difficult.
Other issues are that some duel classes (u get to choose 2) are stupidily easy while some are insanely difficult. If you don't get the balance of dex/str/int right you will really struggle.
On one fire elemental class you have a passive skill that kills all enemies that stand next to you but it's far too powerful... so all you have to do is run into a group of say 10 enemies and stand still. They will all die before you do.
The path finding AI is awful and I suspect may be why there is some lag on many lowerend systems.
I enjoyed this game but only just! Why they made certain aspects of the game the way they did is just strange as it turns the game from a 80+ rated game to a 70+ rated game.