I have done about 11000miles with DI2 (6770 ultegra 10 speed) I really like it and would recommend it, but with the 6770 you have to be a bit careful as shimano no longer make the rear mech, which seems to be the part that gets broken the most.
I had to replace the cable that contains the charge light and manual trim buttons after it was damaged in a strip down service (they denied breaking it, but funny how the bike worked ok before) This meant the battery would only hold a charge for a day, it took me a while to find out what it was and I just charged the battery every night until it was put on the diagnostic tool at another bike shop (that I now use instead) and they traced the problem in a couple of minutes. The new cable was £24 and has been fine since. I had to replace the rear mech after an accident and thats how I know Shimano no longer make that part. I got lucky and found one a shop had left on the shelf, but generally
ebay prices for a second hand 10 speed rear mech than the 11 speed new.
I like the shifting, especially up hills. If you are in the wrong gear it changes without the grinding noises that the mechanical mechs I have used tended to make! By far the best bit is changing the front mech though, the noise is cool! It is easy to set up and you can even trim the rear mech while riding the bike, but I once I have set it up I have had not had to adjust it unless I change the rear wheel out for a different one (they should all be the same, but in practice they all seem to be a little bit different) I suppose that is one advantage of the DI2, it is very easy to set the rear mech on the fly.
I use my DI2 bike for everything, so it has done winter commuting without any problems. I am now slowly getting parts for the dura ace 11 speed DI2. I will put that on my best bike and put the 10 speed parts on another frame and I will use that for commuting. My bike shop cannot believe I use a DI2 groupset for commuting, but why not?
