hedwards: Personally, I'm looking forward to Torchlight 2 as it appears to be in many ways what Diablo 3 should have been and IIRC Runic has some of the same people working their that had worked on previous Diablo games.
The modability alone is likely to make it worth buying.
PoSSeSSeDCoW: Hopefully Torchlight 2 gets a big community. The reason I quickly got tired of the original Torchlight is that I find games of the genre (the Diablo series included) tedious without the social component that multiplayer brings. With multiplayer and a bit more variety Torchlight would have been a great game.
Completely agree, Torchlight is great, but once you get through it the first time there's very little reason to go back and do it again.
I've found Diablo 2 to be more forgiving in that regards than Diablo, but Blizzard isn't particularly friendly with mod makers and they can be kind of a pain to install.
Ultimately, it remains to be seen, however from what I've seen of the new features I think it's going to be a lot more interesting to mod. Particularly since there will be a new set of tools and the ability to play online.
EDIT: Plus the system requirements are likely to be low enough that pretty much anybody that's interested in playing will be able to. Chances are my laptop will be able to run it.