Going from the demo, Torchlight seems to be best described as Diablo 1.5, or even an expansion to Diablo 1 if you're feeling ungenerous. Take note, this game is not like Steampunk Diablo, it very fucking literally is Steampunk Diablo, right the hell down to the town music. There are obviously a lot of little modern changes to the original game's formula - the game is a little bit nicer about where you can stop and continue, you get a little Nethack-esque pet that sometimes doubles as a portable shop, there's a sort of gem system and horadric combinator thrown in and for some reason a god damn fishing minigame - but when you get right down to the nitty gritty it just feels like a sequel to the first Diablo, yet somehow not as much of one as Diablo II was. This is not a bad thing for everybody, I suppose.
Also the game is so far surprisingly easy. I'm playing on the second-to-hardest difficulty and I've had to heal maybe twice, playing a melee dude. I'm sure the game ratchets up the HURT YOU eventually but it's odd to get through levels by blindly clicking shit when the source material had no qualms about making you wish you had never turned on the game the second you walk into the church.