If there's one major criticism that can be levelled at Dark Souls, at least by PC players, it's the rushed nature of the port from console to PC, one major bug-bare of which was it's poor handling of mouse controls. Fear no longer, however, as, once again, mods to the rescue!
There were many things wrong with the PC port of Dark Souls, ranging from a fixed internal rendering resolution that could not be changed, to low quality textures that would have had room for improvement compared to the console versions. These issues can almost all be fixed by various mods, but one major issue that couldn't be fixed was the strange mouse control mechanics, that is, until now.
The reason why Dark Souls' PC port had such terrible mouse controls was ultimately down to how it was implemented. Rather than go to the trouble of doing the job properly, an emulation layer simply takes your mouse movements and then converts them into the controller inputs that the game is looking for. To try and compensate for the obvious problems associated with this, mouse smoothing and acceleration makes the experience very floaty, non-precise, and well, terrible.
DarkSoulsMouseFix does what the developer never managed to achieve, and removes this emulation layer, meaning much more accurate and natural feeling mouse input. The change is immediately noticeable and makes playing the game on PC and mouse a whole new experience, one that it should have been from day way.
It's not just fixing basic wrongs, though. New options allow you to finally adjust sensitivity in both the horizontal and vertical, rebind mouse buttons to any preferred actions, proper hiding and showing of cursors based on weather a menu UI is displaying, and improvements to target switching.
It's not completely perfect just yet, as some users on Reddit have noted, but the overall feedback so far is overwhelmingly positive. You can find the download link, along with some instructions, here.