This is a fantastic fitness tracker! I had a Nike+ Fuelband that I got as a gift before this and while it did not track a whole lot of meaningful data, it did provide me motivation to reach my daily goal and made the whole experience of exercising into a fun little activity. It gamified my daily activities, by giving some trophies and such. So, I finally decided to get a more fully featured fitness tracker. After much research, I decided to settle on Fitbit and I further decided to get the Blaze as it is new, had more features than the Charge HR and has a very usable touch screen display.1. BUILD QUALITY (Size and weight):One fear I had when getting the fitbit blaze was its size and weight. I previously used to wear a fairly large traditional watch by Casio, and it was big and clunky and heavy. The band was also very irritating. I later stopped wearing it completely as a result. The Nike+ Fuelband was tiny, about have the size of the Fitbit Blaze and was very light and so I was very comfortable wearing it everyday. I did not even feel it was there. So I was worried that if the Fitbit was too heavy, I may not wear it regularly.Much to my delight, the fitbit was very light. The first time I wore it, it felt as light as a feather and I could hardly feel it on my wrist! The first impression I got was extremely positive and made me very happy indeed! Secondly, the size of the device is very small. It is about as thin as a regular watch, perhaps even thinner than some chunky watches! It's easily half a centimeter thinner than my traditional Casio watch, so I suspect this to be about as thin as some of those expensive and elegant timepieces! It is definitely far thinner than the smartwatches in the market and while this is not a smartwatch and doesn't have all the bells and whistle that come with that term, it is still impressively thin. I am extremely surprised and pleased by the build quality. Fitbit have outdone themselves and managed to squeeze in all this tech in such a tiny and light package! You won't feel or look weird wearing this in a formal setting.>> A NEGATIVE:I don't have any irritation with the default, black band so that is super cool! But one gripe I do have with the build is the need to remove the main device from its casing to charge. This is inconvenient and may cause unnecessary wear-and-tear. But the folks at Fitbit's Help forums seem to believe that should not be a problem so I hope it doesn't become a problem.2. INTERFACE:Now, with the actual device: the touch screen is very responsive and bright even in broad daylight. It has a sensor to adjust brightness and makes it bright outdoors and dim indoors, saving battery. The interface is intuitive, you have the main watch face, and swipe left to access additional menus and interface from the right side. Tap the screen to get into any main menu item and continue on. You can store upto 7 exercise shortcuts to activate them right from the Fitbit, you can look at stat summary for the day, you can have silent alarms, stopwatch, countdown timer. The silent alarms can only be set on the phone and then synced to the Fitbit, although once synced you can selectively enable/disable them from the Fitbit. You have the FitStar which gives you guided workouts although I have not used it yet.>> A NEGATIVE:You can choose from up to 4 different watch faces, and while they are decent that is a VERY small choice. Folks at the Fitbit help forums seem to suggest that more are coming, but still we need a LOT more. Compared to the smartwatches in the market, 4 is a laughably small number of options. And the smartwatches have the option of creating custom third-party watch faces. I hope that Fitbit not only realizes a lot more first-party options, but allows some kind of a marketplace to allow third-parties to create custom looks to this awesome device! MAKE THIS HAPPEN!3. FITNESS TRACKING:The main thing anyone would buy this product is for its fitness tracking and here it excels! I am not a expert reviewer of these types of devices, nor did I use a ton of different devices to compare with. But, I have used this device extensively for about 3 weeks now and it excels in this department wonderfully. First, the resting heart rate and heart rate in low activities is measured perfectly. I've taken my pulse on several occasions to compare with the reading from the Fitbit, while I was resting and it was spot on. I needn't even wear it very tight to get perfect measurements. As reviewers have noted, in very intense activities, it may be more inaccurate, but that is expected in this type of optical HR monitors. Sleep tracking is pretty good as well, and while there isn't a whole lot of detail except for number of times awake and restless, the automatic sleep detection is very accurate. It is very comfortable to wear during sleep as well, and I got used to it in no time.The step count, calorie burned, floors climbed seemed fairly reasonable and consistent. While the step count may be inaccurate, it is at least consistent, i.e. the inaccuracies are the same over time and across readings and helps compare yourself against your previous measurements. Also, by adjusting the stride length on Fitbit's website you can make the distance measurement more accurate. The mobile app is very well made as well and has a lot of useful details. Pairing was relatively easy and quick and it finds my Fitbit very easily to sync whenever I try to sync it. One tiny gripe with the Android app, which is mostly an Android issue, is that I need to turn on data, bluetooth AND location services to be able to sync the device, which seems a bit too much. Apparently, without location services active, the app cannot get the MAC address of the Fitbit.The assisted GPS with the help of the phone is very accurate and shouldn't be too inconvenient for most people. While hardcore athletes may not want to carry a phone with them when they train, this product is not really aimed at them. And for the rest of us, we would have the phone anyway for music and calls. Plus, while I never owned the Fitbit Surge, it appears that the Surge's built-in GPS was not very accurate at all anyway. So, trading built-in GPS for more accurate GPS from the phone is a trade-off I am willing to accept.4. BATTERY LIFE:Amazing. While it is decent to average according to fitness tracker standards, it is miles ahead of smartwatches. It gives you about 5 days of regular use, while smartwatches can only muster a day or two. What is impressive about this is that Fitbit manages to squeeze so much battery into such a small package, much smaller than many smartwatches, and that too while powering a full-color and touchscreen display. Other fitness trackers cannot boast about the latter part and that's what's impressive. And this long battery life softens the blow of needing to remove the tracker from its housing every time you need to recharge it - at least you do it only once every 5 days!4. SMARTWATCH-LIKE FEATURES:The smartwach-like features were pretty reasonable but limited. The Blaze can get some limited notifications from a connected phone and control music. The music control requires you to pair the Blaze bluetooth in classic mode with the phone. This took a lot of effort to setup initially and was frustrating. But once setup it was mostly seamless. The disadvantage is that you can control music only when not recording an activity on the Blaze as when recording a workout, the interface gives you no option to control music, which in my opinion is a huge mistake. Most of the time when I am interested in music control, I am recording a workout with the Blaze!The notifications are pretty decent but it only allows you to get notified of text messages and calls and calendar events. You cannot answer calls from the Fitbit (I think you can at least pick-up/decline calls if paired with an iPhone but not an Android) and you cannot respond to texts. You cannot get notifications from emails or other apps. And even text messages is limited to a particular app. You can choose to receive text notification from either Google Hangouts, WhatsApp, Facebook Messenger, default SMS app and a few other choices, but you can only pick one of these apps! I would prefer if Fitbit fully bakes this feature and allows us to get notifications from any app. I don't see why this is going to be a technical limitation or even messing with the overall experience of using the Fitbit.In any case, I never bought the Fitbit to serve as a smartwatch and get notifications as I can always pull my phone from my pocket for this purpose. But a more fully baked feature can help others who would also like smartwatch-like features.Overall, I think this is a pretty solid offering from Fitbit. It is my very first Fitbit and I am enjoying every second of using it! I am having a lot of fun pouring over all the stats it collects and hopefully get more healthy over time! I just want Fitbit to incorporate a lot more clock faces and open up the notification platform to enable a lot more notifications! PLEASE DO THIS!