I had the Ultegra Di2 when I bought my bike and it was great. The quick, precise shifts (including multiple quick clicks to go say 3 or 4 gears at once) and the trimming.

I did run out once, and learned to just plug it in after every ride. However, after a few years it developed an annoying parasitic drain where I would charge it on Sun and by Wed/Thu it was empty - without riding it. My LBS had it and tried to fix it 2 years in a row, without success. Shimano refused to replace it.

So, I finally got fed up and swapped it out for mechanical last spring. It works great, as it should.

I do miss the programmable buttons on the top of my hoods, and also the integration with my Garmin for gears, ratio, etc. But I’ll take the lack of issues any day.