How does this compare to the other hack&slash games that are popular right now? I'm thinking of buying, but the price is pretty high compared to Torchlight 2 or Path of Exile.
I haven't played PoE, so I can't comment on it.
TL2's gear is completely random, to the point of +bow skills on an axe. The combat is stiff, environments feel samey, the art is cartoony. The stats system presents the exact same problem they always do: each class has one ideal setup that's better than everything else by a mile, so pick that one or suffer. Fishing is a thing, if you love stopping in the middle of a level to stare at a cursor for a few minutes.
D3's combat is more fast-paced and fluid, with no pigeonholing enforced by stats and point-buy skills. Most of the gear is intelligently rolled, so you don't find much int gear on a strength class, or whatever. It's reasonably efficient to gear up a character via crafting if you wish to do so. There's no longer enforced thrice-over campaign grinding to level up a character.
However, the story in vanilla's pretty bad; if you expect hack n slash titles to be some kind of literary masterpiece you'll be disappointed. It's much better in Reaper of Souls, though.
From what I gather among the three games,
If you don't give a damn about quality or longevity and want something cheap, TL2 seems to satisfy for a single playthrough, as long as you don't look too deep under the hood to see what's broken.
If you thought D2 was the pinnacle of gaming despite its myriad errors and unresolved problems, PoE gets pretty close to that, though the skill tree looked painfully clunky to me, enough to turn me off the game entirely.
If you like hacking and stabbing for some mindless entertainment, D3 fits the bill. It costs more than TL2, but is far more polished mechanics-wise. It's also a magnet for everyone's bitching whether they've played the game or not, and nothing at all about the game can be right, ever. So there's a shit community attached to it, but the game itself is lots of fun.
I can't comment on Torchlight 2 since I haven't played it, but I don't hear it mentioned a lot next to PoE and D3.
The thread for it on this forums should tell you all you need to know. The reaction was something like "omfg this isn't D3 at all! How amazing and magical!" and then the thread died after about 15 pages because the game lacks depth or a soul.