The very latest Di2 groupset from Shimano, Ultegra 6870 is the Ultegra 6800 with the upgrade to electronic shifting.
I took the plunge to electronic, and I'm glad I did. I waited until the new Ultegra 6870 was released because of the improvements over the prior generation. The system is very easy to set up. It's no more complicated than plugging a lamp into the wall. The hardest part of the installation is concealing the wires if you don't have a Di2 specific frame. The shifting is superb. Both in front and in back. Merlin provided great service as well.
Smooth and precise shifting, so glad I waited for the 11 speed with internal battery. Easy to change shift buttons using Shimano Etube through PC if you want. It even shifts perfectly when under load. Riding my other mechanical groupset bike will now be a let down. Yes it's well over double the price of the ultegra mechanical but totally worth it. Plus great service from Merlin! Thanks