I've had my 880 for over a year. The battery holds a usable charge for around 10-12 days. I do occasionally have problems charging--I can't just drop the remote into the cradle, sometimes it's painstaking to get it lined up & charging.
Logitech Harmony 880 Sony HDTV, Sony 400-disc DVD, Verizon HD, H/K AVR-330, X10 home control, Wii, PS3