I've been waivering over whether to call Darkstone a Diablo-clone or excuse its similarities as being merely inspired by Diablo. Having played a good deal of the game, I do have to say that it is a Diablo-clone, but Darkstone is a good game with some strengths of its own.
Darkstone does have the isometric view that Diablo had and it does involve exploring dungeons to advance your characters and complete quests, but it takes an innovative approach. Darkstone is fully 3D with camera controls similar to the Myth game. The zoom in/out feature is very useful and smooth. For the most part graphics look good when zoomed in on also.
You can control a party of two and it is highly recommended that you choose two different classes (fighter/thief, priest/amazon). This is well done and the characters look great. The AI is a little tricky, but for the most part it is good to have someone watching your back.
There are parts of Darkstone that take place outdoors as well. One of the quests I undertook was to help a village whose women had been turned to stoned by an evil witch. Once you have visited a location, there is an option to click on the location's name and your characters will run there.
The town, from which your characters set out, is very nice too. It seems well populated and key shops are grouped together. There is also a bank where you can store your money. In addition to purchasing weapons and magic, you can stay in an inn which restores your health/mana/food meters, and learn skills which help define your character. There is even a training ground where you can practice combat.
One final note, Darkstone does not use class restrictions for items, only stat restrictions. Meaning that while a wizard can use a sword, he may have trouble due to strength and dexterity.
This will be a long list :) but mostly some quibbles.
AI- While you control one character, the computer controls the other. In Fallout 2, you could tinker with the computer controlled character's AI. Here they seem to charge into combat. I had been hoping that my wizard would cast spells while my fighter hacked and slashed, but the wizard joined the fray with his staff. Also, I would have like to told the computer to attack a monster other than the one I was attacking, etc.
The Dungeon- At least so far anyway, it seems unoriginal. It is randomly generated but reuses similar elements from previous levels.
The interface- Mostly good, but a TERRIBLE font. The font they use on the interface is small and illegible. I had to return to the manual to know where to click. Also no spell/skill descriptions are given which means you have to return to the manual. Finally, a quest log would have been a brilliant addition, but that might have been copying Diablo too much.
Graphics- Once again, mostly good. But I've seen items hop over walls when chests are opened. Also characters seem to stand right on the objects which means you have to back them off to pick anything up. And, while characters look good, their shadows are pixellated.
Controls- Good 3D camera system, but I wish I could re-map the keyboard to use the standard w,a,s,d rather than the number pad, which is too close to the mouse.
The Bottom Line
This is a Diablo-clone, but wasn't Diablo a Gauntlet-clone? This is a fun dungeon crawl, slower paced than Diablo, but with more rpg elements. I would describe it as Diablo creeping towards Baldur's Gate.