Very nice tracker for heart rate and sleep, but is WAY off on step counts.I bought this primarily for the continuous heart rate and ""smart"" sleep tracking. I have a good smartwatch that has Google Fit for keeping track of steps, and it's pretty good. For today, as an example, Fit says I've walked 8620 step (yeah, I knowit's hard to get to 10K when you have a desk job though!) and the Band 2 Pro says I've walked 11262 steps. That's a pretty significant difference, so I tested them. I wrote down the stop count on both devices, walked 250 steps, then checkedFit recorded 235 steps while the Band 2 recorded 341 steps!The only other knock I have is that every three days or so, the band gets disconnected from my phone and I have to restart the phone to get the band to connect. That's quite a hassle, but in the 12 days I've had this band, I've gotten two software updates, so it seems the company is staying on top of things and I'm hopeful the connection issue will be taken care of soon.The band is kind of flimsy and the ""push these two tabs through two slots"" design is really scary when you are moving around a lot. I've had the band come unclasped a couple times already, but luckily my hands are so big the band can't slide off unless the clasp goes through the loop and is completely open. (I ordered a leather replacement band from ChinaI'll let you know what I think once it finally gets here.)Okay, now for the good stuff.The heart rate sensor is surprisingly accurate. I have a blood-pressure cuff that also counts heart rate and every time I check it, the Band 2 is within 4 or 5 BPM of the cuff, so I'm very happy about that.The sleep sensor is very goodit can even tell (somehow) when I'm laying in bed reading before I go to sleep, because the ""in bed"" time on the app is invariably the time I stopped reading and went to sleep instead of the time I laid down.The app is pretty good. It has separate cards showing summaries of your sleep, heart rate, exercise time, etc. and you can click on a card and get a more detailed, daily presentation of the data.I wish there was a way to zoom in more on the data in the app or to easily download the data to my computer so I could save it in a spreadsheetbut just because I have a big ""I wish"" list doesn't mean the app isn't good.Battery life is excellentif you don't use the exercise tracker with GPS turned on. That's not an issue for me, I use my smartwatch to track bike rides and walks. I haven't used the GPS much so far, but it really does seem to drain the battery pretty fast. I wish there was a way to reducing the sampling rate or something and save a bit of battery, but maybe that will happen in a future firmware update.Without using the GPS, I get right at 10% per day out of the battery, so it's easily lasting a week between charges.I give it a solid 85/100lowering GPS usage during outdoor exercise and having a more accurate step count would push it really close to perfect.