Bests & Worsts Reviews from Amazon

First things first: If you fasten/unfasten the clasp a few times (it took me 3 times), the holes in the band will loosen up and the Flex is very easy to take off/put on from that point forward. The very first review of the Flex here made that point quite clearly. Second, there is a reason there's no manual: generally, people don't read them. That's why you need to go to the website to initialize your Flex, and, hopefully, read the other instructions. FOR EXAMPLE: If your results are really inaccurate, you may need to change the default from Non-Dominant wrist (sensitive calibration) to Dominant wrist (less sensitive). [My experience: I'm using it on my non-dominant wrist, and I spend much of the day on the computer. I'm right-handed, and that's the hand I use for mouse/touchpad. My Flex is on my left (non-dominant) hand, and my results are well within my expectations for other movement.] Third, MEASURE YOUR STRIDE. If you walk, as I do, try this: Put a pencil or other straight object on the ground, just behind your heels. Walk 10 steps, bringing your heels together on the last step. Put another object behind your heels. Measure the distance in inches between the two straightedges and divide by ten. Bingo: You just got a fairly accurate stride. If you are a runner, run a known, accurately measured distance, **counting your steps.** Divide the distance by steps and convert to inches. No, the Flex doesn't have an altimeter, so it can't measure "flights of stairs." (Neither can the One, actually: it measures 10' changes in elevation.) But nothing in the Flex's literature should have given you any impression that it has an altimeter. So not having something it never purported to have, is not a problem with the device. If you do even the most basic research, you'll know the Flex only syncs via Bluetooth to a very, very few Samsung devices (two or three, I believe) and iPhones/iPads. On the other hand, it doesn't suck your Android's battery if you can't sync via Bluetooth. It takes _maybe_ two seconds to sync to my computer via the USB device, and by the time I look at my phone or tablet, the updated info is in both the Fitbit app *and* MyFitnessPal. (If you really want to sync to your phone or tablet, there are cables available to accept the Flex's USB dongle, and plug into a micro-USB port.) Before getting my Flex, I was using the Android app CardioTrainer. I'm still using CardioTrainer, because (a) it's on my phone and (b) I get to listen to music while I walk. The step counts between the Flex and CardioTrainer are within 1 percent of each other (using the same stride length, and having the phone in a back pocket). No, of course the Flex isn't a heart-rate monitor. So no, of course it's not going to *precisely* tell you how many calories you've burned. But the algorithm should be useful for the vast majority of people. If need or want pinpoint accuracy, then yes, you need a heart-rate monitor. Bottom line: For what it is intended to do, the Flex is as close to perfect as I could ask for. Everything I expected it to do, it does, and very, very well.