Dungeon Siege III isn't heavily dependent on the graphics card meaning that you should be able to enjoy 1080p resolution at max settings with a fairly consistent 60 frames per second on anything from an NVIDIA GTX260 or Radeon HD 5750 upwards. However, from a processing perspective, it appears that the Onyx engine can be CPU-bound, with performance definitely benefitting from ownership of a quad-core processor.
At like-for-like resolutions with the console games, Dungeon Siege III on PC offers up very little in the way of visual enhancements, with the differences mostly confined to some occasionally higher-resolution artwork and improved effects work. However, levelling out the frame-rate makes a night-and-day difference to the way the game looks and plays, and to the overall visual coherency of the game world in general. At 720p the artwork may be too all intents and purposes the same, but the world of Dungeon Siege III moves and flows that much more smoothly and realistically.
There's a very definite sense that the PC game is the "master" version of Dungeon Siege III. It does everything the console releases set out to do and just a little more besides. In comparison with the console versions, it's interesting to note that the mild technical compromises Obsidian made for the 360 and PS3 releases are completely absent in the PC game, which has the best of both worlds. Actual visual improvements to the game are somewhat few and far between, but they are there if you look for them. Anti-aliasing is selectable, with 2x, 4x and 8x MSAA as options, but perhaps because of the post-processing effects blitzing the effect after it has been applied, the overall effect is very similar to the console versions.
Of course, the ability to run in much higher resolutions than the standard console 720p is a welcome addition. During the NPC conversations, you do resolve more detail in the clothes and faces of the characters you're talking to, even though in some cases, close-up low-resolution textures can look a bit poor. There's also a great deal of intricate detail in some of the environmental artwork, clearly apparent at 720p, but far more so when more pixels are allocated to the make-up of the scene.
While it's uncertain whether it can be classed as actual official "support" as such, Dungeon Siege III on PC also works with AMD EyeFinity set-ups, and it also looks a treat on NVIDIA 3D Vision, where the far off-camera angle in particular works extremely well in generating a superb sense of depth as you "look down" into the screen.
The PC version of Dungeon Siege III also seems to support a kind of half-baked auto-save (seemingly completely absent on the console versions - annoyingly so, in fact) and the actual process of saving your process is much faster than it is on Xbox 360 and especially PS3. Quite why a proper auto-checkpointing system couldn't have been implemented is something of a mystery, but at least the PC version makes the most of what is a pretty poor situation.
Where the game fails badly though is in its control scheme. With a gamepad attached to the PC, Dungeon Siege III plays identically to the console versions. However, without one you are left with a poorly conceived keyboard/mouse combo that makes virtually all interactions with the game unnecessarily arduous. Adding to the sense of incredulity is the fact that you're unable to re-bind the keys - effectively you're stuck with the WASD setup the developers have shipped the game with.
While the basic make-up of Dungeon Siege III may well be a bit of a novelty on console, the "dungeon crawler" style is an established gameplay staple on PC and the interface has been refined considerably over the years. In comparison to the existing configuration, the joypad setup actually works well, which helps, but you can't help but feel that Obsidian has let PC gamers down badly by not embracing the freeform flexibility of something along the lines of Torchlight or Diablo.
In an interview with Eurogamer, Obsidian has promised to improve control for PC owners so hopefully this issue will be resolved relatively quickly. While the game is perfectly playable with the pad, it's safe to say that not every PC gamer owns one. In truth, just the basic courtesy of allowing players to re-bind the keys to their liking would have gone a long way in resolving this issue.
The control situation is pretty much the only issue we have with Dungeon Siege III on PC in terms of the game as it stands, though we can't help but feel that the basic combat system is probably rather simplistic and the lack of sophistication in the design may put many off. It also comes across as a game that is inherently limited: all versions could really benefit from the ability to port over your character to a new, tougher version of the game once you have completed it, and regardless of platform, Dungeon Siege III suffers from a poorly thought-out online mode where you can't import your main character into anyone else's game. It works out OK as a local co-op game, and this mode persists on PC, though two gamepads are required.
Overall, Dungeon Siege III isn't an essential purchase, but on console at least it's sufficiently different from the norm to make it worth looking at. In terms of which version is the better purchase, there's really not very much in it: graphics are identical to all but the most intense comparisons, while the PS3's unlocked frame-rate only seems to help marginally in sustaining performance when the engine is really under pressure.
Thankfully, Dungeon Siege III's style of gameplay doesn't rely on lightning-fast reflexes so the frame-rate dips are just a little annoying as opposed to game-breaking. If the lack of consistency in the gameplay experience is an issue for you, the PC version is the answer with even relatively old gaming PCs able to handle the high frame-rates and resolutions where this game truly looks at its best.