After taking out my video card and giving it a good thumping (and some technical details having to do with making sure the fan was seated properly) Titan Quest is now running without making my machine divebomb.
Take that, all you bleeding-edge proponents. MY ANCIENT CARD WORKS JUST FINE.
Okay, so, back to the game. My first character build is, so far, a Rogue/Warfare assassin type - warfare taken so that I can hike my attack speed and get dual-wielding. I want to pounce on people and cut them to ribbons. I also grab the attention of individuals at a distance by throwing knives at them. A lot of them bleed to death before they can mange to reach me. Undead don't bleed. I don't like undead.
Targeting, UNLIKE Lionheart, is smooth and forgiving. I click roughly near a monster, I go kill it. Picking up items is slightly more fiddly, especially since the ground is littered with broken items you don't want to pick up, but that's okay. Slaughter first, then take time to loot.
Positioning and paying attention to it matters. A long-distance magic attack coming towards you can easily be dodged if you're looking. And opening big likely-to-be-trapped chests? Click to open it, then GET OUT OF THE WAY while the opening animation runs and you'll be fine. I don't know if that delay is intended or not, but it works for my sneaky playstyle. I poke things with sticks, then back off.
I have only died once so far, from being jumped on by too many undead to kill at once. Usually I am not in any danger from normal monsters, and am capable of fleeing from bosses. Difference from Diablo - there is a cooldown period on most activities, preventing you from doing them again immediately. THIS INCLUDES DRINKING POTIONS. You cannot just slam ten potions while fighting a big tough thing. You can drink ONE. (Potions also seem weirdly strong, and while I do pick up different sizes of potions, they all stack into one undifferentiated slot.) But again, this really isn't a problem, because my / this character's playstyle is to jump in and out of trouble.