It is absolutely perfect in its functions like steps, GPS, calories, blood oxygen, or the display of brightness; one of the main features is the battery which, with normal use, lasts over 20 days.
For anyone interested

Xiaomi Poco Watch Waterproof with Heart Rate Monitor (Black)
Purchase Date 21/11/24,
with a 2-year warranty
and the receipt in your hands
It has GPS, BLUETOOTH, and is waterproof.
Incredible Battery Life!!!
Any inspection is welcome.
Such a low price due to a promotional purchase. Thank you.

Its measurements are good. It has good sensors and an AMOLED display. During sleep, it shows REM sleep and has a separate oxygen recording. Its battery is good.

For the job I want it, it's very good! You can add photos that you want for the background and it's generally reliable in its measurements. Even for sleep tracking. Unfortunately, I don't see the straps coming off easily if needed, but we'll see when the time comes. Anyway, it fits perfectly with my Poco phone.

Everything works correctly and its measurements are very good. It has very good sensors and GPS, and an AMOLED screen. It shows REM sleep during sleep and has separate oxygen recording if you choose it.
The battery is very good, but I don't use notifications and calls.
The screen is a bit small for me, and I would like a little more customization in the watch faces, as the white color and the position of the time are a bit restrictive and sometimes don't look good when you put your own image.
So far, I haven't been able to replace it without increasing the price significantly, mainly because the Poco measures very well and any "upgrade" I tried was disappointing in terms of measurements.

I simply love it! It withstands both the sea and the hot shower! I have had it for two years and it hasn't suffered any damage! I don't take it out of my hand!

I got it last April. It withstands tough conditions since I use it for kickboxing training. Accuracy in its measurements, long battery life of up to 14 days, and not in inactivity. Comfortable screen, with automatic brightness in the sun. Very satisfied. I bought it for 75 euros and would gladly pay that amount again.
update 3/10/24
unmatched even in open water swimming!

After purchasing it, the synchronization with my device did not happen through pairing by scanning and downloading the application via the Qrcode, but by watching online videos I first downloaded the Xiaomi application directly from the Google Store. Full support in Greek, and the ability to display notifications from calls, messages, and viber/whatsapp. In terms of measurements for everyday use, it is just what it should be and has nothing to envy from other activity trackers, but it is certainly not flawless. The only annoying thing is the mandatory manual process of synchronizing the data between the watch and the device. I believe that it could be programmed to do this automatically during the day, since it is usually constantly connected via Bluetooth.

Very good, value for money, the measurements are not as good as Garmin's but we are going to another category. Very reliable, it does what it says with a small deviation in measurements.

I bought it for my ten-year-old daughter and so far she hasn't had any problems. I believe she will handle it, so it's worth the money.