Had full knee replacement in both knees, left in '08 and right in '12. The left side went quite smooth, no drama, no problems. Because it was so successful, I did not hesitate to get the right side done too.
Recovery was textbook perfect for the left, but the right was a problem child. Could not get the deflection and target angles correct, and had to go back under for 'manipulation.' The doc basically racked the joint back and forth. It was better afterwards, but the overall experience was far less positive than the left knee.
Finally, the surgeon told me the new joints were like new tires; they aren't going to last forever, but, if you don't abuse them, you'll get a much longer service life. Darn! Looks like I picked a bad time to start running marathons.