For $20, this game is DEFINITELY worth playing. I don't play many ARPGs, but Torchlight II has sucked me in.
The fluidity of both combat and exploration is masterfully crafted. Moves flow seamlessly as you run through an area, unsure of what will appear out of obscurity in the fog of war, but knowing it will appear. There are just enough bosses and mini-bosses to keep the pace interesting, without overburdening it with long, tedious fights or repetitive deaths. It's basically the balance all ARPGs strive to achieve, but few are able to execute.
The game is full of "little things" too. I love the menu system. The shortcuts and menus are designed so you can just fly through them and do what you need to do without being overwhelmed by trash or mixing up icons. Once you get the hang of it, the UI is actually very intuitive.
Of course one of the best things about TL2 is your pet. At its most basic level it's what you'd think....an AI companion that helps you fight baddies. And of course it helps that it's a total bad ass. But it get's so much deeper. The 4-slot spell system adds a level of strategy to the game. Would you rather have an attack pet with fireballs and minions? Or a defensive pet with heal spells and buffs? Or a balance of both? It can change your entire play style and how you approach a fight, consequently giving you a whole new experience. Throw in randomized dungeons/enemies, and the replay value from combat alone is tremendous. But one of my favorite pet features is the delivery system. When your inventory gets full, you can actually give any item to your pet and tell them to fly to town to sell it all and/or pick you up a few things like scrolls or potions. It's also a nice temporary bump in difficulty to see what you're really capable of.
Not that you need it. This game is tough, even on normal difficulty. You always have to be on your toes and if you get cocky, it may very well mean the end. The death system is interesting: when you die, you have three options - rez at the town for free, rez at the beginning of the dungeon for a decent chunk of gold, rez where you died for a large chunk of gold. Some people hate it, I think it's pretty nifty.
Sadly TL2 isn't perfect. I'm not a HUGE fan of the graphics. They were probably what pushed me away most at first to be honest. Especially with Diablo 3 on the other hand, the comparison had to be made. And i'm not like a graphics fanboy or anything, I play all games. Not so much about the quality itself, I just wasn't thrilled about another cartoony fantasy engine that just looks a little outdated. Not the end of the world, but with everything out today, it stands out. And while the combat is totally fun, sometimes it can become a kite fest. Not often, and it's not terrible, but again...it's noticeable. Part of me wishes there was some WASD functionality, but that would also take away from the menu/UI that I've come to love. So the point/click system can take some getting used to if you're not a big ARPG gamer, and more than once have I defaulted to WASD in the midst of battle, only to open up all my menus and inventory as my health is whittled away. So I dunno, just a minor annoyance I felt worth mentioning to someone in a similar position as I was. Definitely not a deal breaker though.
Anyways I'm sure I'll be back to add more. This is what all stood out to me the most as I wrote this. Overall this is a great game, and if you get that ARPG "hunger" the way I did, but don't want to overpay for Diablo 3 and be forced into DRM mayhem....then the choice is really that simple.