I am a bit concerned about the hr sensor. So far I have only one cycle trainer session to go on, but for about the first 8 minutes, the Bands hr reading was running 30 to 40 bpm high compared to my chest strap. After that, it appeared to settle down, and tracked within a beat or two of the strap for the next 40 minutes or so, including the test section (it was a 60 minute total-20 minute ftp test). During the cool-down at the end of the activity, once again it stayed up 30 to 40 bpm too high for about 5 minutes, then settled back down and tracked pretty close to the strap until the end. The strap's graph indicates a slow and steady ramp-up of hr for the warm-up, which is expected. The Band quickly jumped up within seconds. Again, during cool-down, the strap recorded a slow and steady decline, whereas the Band held up high, then suddenly dropped to something more believable. It seems to me to be related specifically to how the sensor reacts to increase or decrease in HR. Although, there were a couple of intervals leading up to the ftp test, and it seemed to react reasonably well to them. Hopefully this will be fine-tuned with a firmware update shortly.
Another thing. Although the activity synced to the app almost immediately, it has been almost three hours since the workout, and it still doesn't show up on the web portal. Not sure what's up with that, or if it has anything to do with Band 2 vs. Band 1. Could well be a site problem totally unrelated to Band 1, but I don't remember it ever happening when I was using Band 1.