I'm with James Madison and those guys in Philly 225 years ago who considered and rejected term limits:
"a few of the members of Congress will possess superior talents; will by frequent re-elections, become members of long standing; will be thoroughly masters of the public business, and perhaps not unwilling to avail themselves of those advantages. The greater the proportion of new members of Congress, and the less the information of the bulk of the members, the more apt they be to fall into the snares that may be laid before them."
I would prefer much tougher campaign finance reform and ethics/lobbying reform.
Another downside to term limits is that it would likely make unelected Congressional staff much more powerful, unless you term limit them as well.