You have to play the beta to understand. I myself confess I found TL1 to be a bit of a grindfest, but TL2 beta is just phenomenal. Here is a list of things that weren't in TL1 that are in TL2:

Skills with visual enhancement (they look cooler at higher levels), and new passive additions as they level.

Character customization along with male and female variants for every class. Also gear is no longer the cookie cutter seperate for each class armor crap system the last game used. The system has been entirely overhauled so that almost any class can use any armor.

86% more gear and items (Every item is new, but almost double in sheer content than the first for the same price)

Random encounters (Seriously, there is a constant flow of unique little things varying from altars summoning mini survival rounds, phasebeasts, and a plethora of other little doobobs)

Unique Bossfights, just ask those who have played even D3. TL2 has some really cool, unique boss fights which are quite exceptional for the ARPG genre (particularly hack n slash)

To say that it "has just been brought on par with D2" would be rather foolish, as while D2 was in excellent game in its time, if it were released nowadays (even with updated graphics) it would be hailed as clunky and even grindy.

You can read an official review here: http://www.examiner.com/review/torchlight-ii-review-just-buy-it-already, the classes are very unique and really don't play like TL1 classes or D2 classes at all. It is an entirely new experience from TL1 and is executed to perfection.