I like this but is capped at using a 28t cassette. The new 9170 can go to a 30t if you have plenty of hills to contend with and don't want to run an Ultegra di2 with a longer cage.
I upgraded from the older ultegra 10-speed shifters to this one. The 11-speed works well. I installed it and the derailleur myself and worked like a charm. You can download the installation manual from Shimano's web site, which was helpful.