His strength as a candidate will depend on what happens to the economy between now and November.
If the stars and the moon align, and the Ron Paul coalition takes off, that opens the door for another third party candidate, Mike Bloomburg, who will represent a coalition of moderate republicans and democrats.
The far left don’t like him, check out these articles by Noam Chomsky and his cohorts railing against Ron Paul:
http://dandelionsalad.wordpress.com/2007/12/23/noam-chomsky-on-ron-paul/
http://dandelionsalad.wordpress.com/2007/12/01/on-the-issues-dennis-kucinich-and-ron-paul-by-lo/
Most of the Democrats he’s attracting seem to be middle class/educated suburbanites who are fiscally conservative/socially moderate and have voted Democrat in recent years because they view the GOP as having been taken over by the Huckabee/big govt types, as well as independents who defected to the Dems in 2006 because of Abramoff&Iraq.