I'm annoyed with battery-saver mode—the 255 prompts battery-saver mode when the battery is low/dead. I don't understand the point of turning off all the sensors on the watch. At this point, the watch does what exactly? It even happens after the watch is fully charged. So annoying...
It took me an hour of searching to get the battery saver turned off (the watch was 100% charged). Pretty sure there's a bug in the UI for turning off the "feature". When you go to the heart rate monitor and it says battery saver is on, how about letting us turn off the feature from there?
I own the 235, 245 music, 255, and I have the 265 in a box. The battery-saver prompt is the worst feature by far.