People say it's like Titan Quest.... well, it IS Titan Quest. OK, just the engine. Beyond the interface similarities, it is most definitely NOT Titan Quest!
This game is often described as "the spiritual successor to Diablo 2," or, "the game Diablo 3 should have been."
I whole-heartedly agree.
If you want to play the dark, gritty, frightening and violent game Diablo 3 would have been if not for the radical departure from the tone and story of the first 2 Diablo games, you need to play Grim Dawn.
It's deep, complex, has great replayability despite the lack of procedural maps, and offers FAR more in terms of deep lore, content, exploration, challenge, and payoff.
PLAY IT. You won't regret it.
Just don't expect it to hold your hand.