When it comes to the drawbacks, I learned a few things I had previously been blissfully ignorant of.
First, a pedometer; I bought the bracelet thinking I could use it to keep track of my runs without using my phone at all, which would be distracting while on the go. In the past, I've used a ruler and paper maps to measure my daily 3 km distance, so I have no reason to doubt the range of the distance (I account for the error of + - 100 m). In fact, in the "training - running outdoors" mode when running without headphones, the distance is displayed accurately even when there is no cell service. The steps and average speed are calculated by the phone's pedometer. Thus, he produced the same results in the initial 3 km races, indicating the finish of the distance with an accuracy of +/- 100 meters. In successive races, as my running speed increased, the bracelet began to indicate that I had run 1 kilometer later by 50-100 meters, and so on; overall throughout training, I ran 3.4 km, while the bracelet showed 3 km. As I do not yet understand the data that defines such a run, I plan to get a running belt to attach my phone to in order to take updated measures.
When it comes to music, the feature is mostly operational, but there is a subtlety to consider. I tried using this feature while out and about in the city, and it worked great up until the bracelet's screen changed. In other words, if I have one track playing and the bracelet screen goes out and I decide to switch it without listening to it, then everything is fine; however, if the track switched and the screen went out, and I decided to switch to the next song, then in this case, my screen displays the name of the old song even though it sounds different, and when you try to switch the track, the bracelet gives a message in the spirit of "turn on the music on your phone." I thought restarting the bracelet would fix the issue, but it happened again afterward. Perhaps the programmers will eventually fix this subtlety, however as it stands this function produces negative results.