For anyone on Nvidia hardware that's having issues with stutter - a fix has been posted on the Steam forums.
You just need to force vsync in the Nvidia control panel and use the frame limiter in MSI Afterburner. It's not in the Afterburner-proper program, but in the On-Screen Display Server applet that comes with it. FYI - Afterburner works with any hardware, not just MSI...
Darksiders is one of those few oddball programs that has a default maximum FPS that's an oddball number, and it doesn't jive with some hardware. Some other people have reported that running it in a window and D3DOverrider can also work.
This doesn't suddenly make the game look any better, but it's at least playable now.
Have people successfully forced options in Nvidia control panel and/or with Inspector? Or AMD equivalents?
I can tell you that the FXAA Injector for Skyrim does a nice job with this thing. Preset 1. Toggle the gamma up one notch and that's all I had to do. Looks great.