I wouldn't vote for him, and that's not just because I can't.
His economic principles are flawed, mainly that he fails to realize that a central bank like the Fed is absolutely essential for a viable modern economy. Lowering taxes is the complete opposite of what this country needs in the long term, if it wants to fix its deficit. His free market principles are fine by me, although I would like him to stop "opposing federal interference" and then supporting earmarks that subsidize businesses in Texas. The one good economic proposal he's proposed (that I am aware of) is an "opt-out" option for Americans who don't want Social Security.
Limited government is a big issue. While it always is tossed around that big government is a problem, many vital functions are performed by this big federal government that would be cut if Ron Paul had his way, specifically the elimination of the IRS, Department of Energy, FEMA, Department of Commerce, & the Department of Health and Human Services.
Everything he has said about civil liberties makes complete sense to me, so that part of his record is more or less spotless in my eyes.
His record on environmentalism is mostly clean in my book, although his dismissal of climate change is somewhat disappointing.
While I do like the idea of non-intervention, Ron Paul seems to be advocating almost outright isolationism. We should certainly reduce our involvement in other nations' domestic affairs, but I support foreign aid (in general) and counter-terrorism efforts in hotspots like Yemen.
I don't like to dwell on healthcare (as I am not too knowledgeable about this subject), but I do like his support for legalizing marijuana and ending the War on Drugs. Saying that government should stay out of the healthcare business seems downright silly though.