I'm running Di2 on a couple of bikes, and have no complaints. There was a little bit of a learning curve when converting away from mechanical shifting. Choosing the best wire lengths, wire routing, battery location, making sure the connections are properly made, etc. But installation and fine tuning is not difficult, and I love the fast and precise shifting. One of my bikes is a 1x12, the other a 2x11, both systems work beautifully.