It is a rather boring arpg game, it lacks the depth and customization of free to play games such as Path of exile. Basically I measure every arpg against Path of exile and every other arpg is really shallow compared to it. I played both torchlight 1 and 2 and both of them were very easy to put down once new challenge league starts in Path of exile. Uninstalled both torchlight games and never looked back.
You got a hero that runs around, fights and accumulates gold, gear and experience. The hero is persistent throughout the campaign. The game is similar in vein to king's bounty(except it is not artificially stretched out like king's bounty where you are burned out at the end) and Disciples 1-2 with medieval and dark setting. The quests are really well done, they are stitched into main story with 30% sidequests where you can get great treasure. For the price, totally worth it.