This route is just a couple of minutes from where I live, so I do it frequently. Its an OK (15 minute) ride, but it really isnt worth a special trip and speed limits have been reduced in the last couple of years. The scenery is nice, but it doesnt have much else going for it. The speed limit for most of the ride is 40mph with several portions at 30mph. I dont think that there are any 60mph sections left. The road surface is acceptable, but there are quite a few holes and unstable portions. At 40mph they dont present a problem, but at higher speed they could be quite dangerous.
Latimer road is a nice run with some (short but ) fast straight sections and some nice bends. Only real problem is traffic - theres usually quite a lot!
Beware the speed cameras as you enter Chesham at the end of the run.