Unfortunately, there are no real reviews on the net yet, just glorified marketing. So the reality of the practice. I have a many years old Mi Band 4, its battery still gives over 3 weeks (was 32 days). With the Fit3, after the first two days, 30% down, but I had the automatic exercise detection turned on as well as oxygen in sleep, so the heart rate monitoring etc came on when I walked. I recommend leaving it off.
The power cable has a USB-C connector, so if you want to put it in a regular charger, you still have to buy a USB-C female to USB-A reducer somewhere.
I don't have fat hands, but the belt is on the last hole. I don't recommend it for people with stronger hands, there are no other tapes from China yet. With the MiBand, I used a 3-hole. I'm now wearing both the MiBand4 and Fit3 on the same hand at the same time for comparison. Fit3 is wider incl. the tape, the more your hand sweats under it.
Connected both to Xiaomi 13T PRO, Fit3 requires installation of Samsung Wear, Samsung Health incl. Samsung account, next it will automatically install the Fit3 plugin + something else. If you have a Samsung tlf, Health already installed, maybe Wear too. Functionality:
When the exercise is turned on (automatically or manually) you will not get the notification, you can only turn off the exercise. Quite uncomfortable when walking or running.
Less BT range than MiBand, constantly disconnecting and reconnecting when moving around the apartment. Annoying when you have notifications turned on, plus your mobile phone beeps as if it's a new message, you come to it and there's none there again. But you can turn off the beep in the notification settings of the Fit3 plugin.
100 dials, but only 1-3 are usable, the rest are crap for kids.
Camera controls don't work on non-Samsung phones! That's a stupid intention by Samsung, other BT controls work everywhere.
Sleep tracking was all over the place the first day, the second day was more realistic, I'll see how next.
When it comes to counting steps at rest (normal hand movement, walking around the apartment, etc. ), Fit3 shows up to 50% more false steps than MiBand.
On the other hand, it shows the distance (metres, not steps) when walking outside more realistically, with a shorter stride length set. You can't set this manually, but it seems to automatically calibrate the stride length if you have GPS on. So I recommend to have the GPS turned on when you are out initially.
Notifications take much longer to see on the MiBand and can be viewed multiple times backwards, but on the Fit3 they are only seen once and then deleted on the phone. It does make sense but I would welcome the possibility of adjusting it.
Vibration even at full power is weaker than with the MiBand. The Fit3 of course has a better look, more features, etc. But if we compare the same features with the MiBand4 with the Notify for MiBand app, the setting options are incomparable in favor of the MiBand. Overall, it's not a bad bracelet at all, but I recommend comparing it with the latest Xiaomi when it goes on sale, it's more expensive, but maybe more interesting.