I recently (just before Christmas) bought and fitted the new Shimano 105 5800 11 speed to my Summer steed. Assembled and set up really easily, I'm pleased to say, although absolutely no fitting instructions were in the boxes so I downloaded all the dealer manuals. Rode it a few times just to check the setup and the shifting was crisp and quick. Roll on dry and sunny days.
That said, I'm not sure I even need 11 gears, I just wanted them. I only had 5 as a kid.
Gibbo.