Any drawbacks to using it? Bugs? Permanent changes made to saves (even if you go back to vanilla)?

Not that we know of. There was a documented case in the first release of TESVAL that made scripted events become delayed, but that was fixed.

I downloaded it and it instructs placing just two small files in your Skyrim folder. Is that it? No extraneous stuff like TESVAL requires (the scrip extender thing and setting up folders in the data folder)?

None. If you want to go back simply delete the files.

This mod is currently still in testing phase, but I'll think it'll take off once it's uploaded to the nexus. It's really that great.

Edit:


Nope, it's a stand-alone mod. Does not require a script extender.