Like:

-My chain never rubs, even when cross-chained.
-Zero tuning necessary as there are no cables to get stretched and need any real adjustment.
-Quiet and smooth.
-Front cog shifting is pretty much bullet-proof, even while climbing. I've never had a chain derailment or any problems so far (2500 miles).
-Shifting two or three gears up/down is as easy as hitting the button quickly and my bike is in the proper gear.
-Battery life has not been an issue. I charge my battery once every 3 months or so and have never gotten stuck on the road with a dead battery.

Hate:

-Cost