The other issue I didn't like was you eventually wind up with someone who knows that even if they do the best job ever, they can't be re-elected. The capitalist in my cringes at the thought.
While multiple terms definitely incentivize, it also presents the problem of forcing the politicians to begin campaigning for their next term while still in office (quite possibly hindering performance). Maybe the best solution from an economist's prospective would be to leave out the term limits but to somehow boost the popularity of recall elections.