For everyone commenting on the blur in-game: D3 uses a post-process anti-aliasing technique (perhaps FXAA, and if not something very similar). Instead of anti-aliasing specific pixels, PP AA simply blurs the entire image. In terms of performance it's super low, but because of the game's zoomed out perspective detail gets absolutely annihilated (zoom in on your character and try to see the specific laces and buckles on a pair of boots).
People are pointing to Dark3D as an alternative, which is also a PP technique. Where it differentiates itself is that it's a configurable FXAA injector, allowing you to sharpen or apply other filters in addition to completely changing the color of the game.
If you don't mind the game's aesthetics I would instead suggest disabling the in-game PP AA and using proper multisample anti-aliasing. If you've got anything other than a decrepit system this shouldn't pose a problem performance-wise. This will give you true 1:1 texture clarity and provide a superior level of anti-aliasing (have found that textures with baked in specularity, like the Waypoints, look incredible without a PP blur applied).
On NVIDIA systems download NVIDIA Inspector:
http://downloads.guru3d.com/NVIDIA-Inspector-1.94-download-2612.html
Then set up your profile as shown and disable the in-game AA option:
If you have performance issues with 8xQ MSAA simply lower the value.
On AMD systems, ask someone who has an AMD video card, because I haven't got a clue