It did not have a CR2450 battery. It was not stated. There are other Sonoff Zigbee sensors that had a battery (the sensor was round, not square. Theoretically, they are the same)

It cannot connect to anything on Wi-Fi. I have made many attempts and on different networks but it absolutely cannot connect

Very bad. You set it up and it plays for a day and then breaks again. You set it up again and the same thing happens. It's not a battery issue and I have also bought other zigbee products that work fine. Maybe this one breaks because it sends temperature periodically. In any case, it is not reliable

Attention, it does not work on its own, it requires an additional component (bridge) to connect to the mobile phone. This component requires changes to the Wi-Fi and it is a huge mess. It requires 2.4 GHz and not 5.0 GHz, and good luck trying to navigate through the router settings to figure it out

The only way to stay connected is a patent to continuously receive power from a USB port with a conversion of 5V->3V. Otherwise, with a battery, it constantly loses connection with the antenna at 1 meter...

It connected very easily to the Sonoff ZBBridge Smart Hub. The measurements appear accurate compared to other thermometers.
It is unacceptable that it did not come with a battery (cr2450) and had to be purchased separately (not mentioned anywhere).

I have had it installed for 5 months and it works flawlessly.
What I don't like: Google Home only reads humidity while Alexa only reads temperature. And both together only in ewelink

It measures accurately and temperature and humidity. I put it in November and the battery still shows that it is full. Therefore, I recommend it. Better placement not near a window because the measurements will not be accurate.

Honest temperature/humidity sensor.
I don't have an opinion yet on how long its battery lasts.

Edit:
If it disconnects (which has recently started happening), it never reconnects, it needs re-pairing.

Edit 2:
When it disconnects, it drains the entire battery. It's not worth it after all.

If you upgrade to ewelink, you will have to pay 11.00 euros to unlock the program's capabilities for one year. Then you will be able to set up the sensor, otherwise don't get it.

Easy installation and synchronization. Works fine with Google Assistant and Alexa. But when going about 10 meters away (2 rooms), where it was far from the hub, it couldn't transfer data.

Having an old electronic thermometer, the difference was very small, 0.3-0.5, it just takes time to synchronize with the room temperature when you open it (from 24 degrees Celsius when I opened it, until it reached 18.4 degrees Celsius in the room, it took over 20-30 minutes), and yet I'm not sure how much difference it has for humidity. I need to find a way to check it with other devices.

Unfortunately, they break for fun. I bought 4, one broke in the first week, I replaced it, and 2-3 months later another one broke. Also, the battery measurements are completely random, it can show 70% and the next day 90%. As for temperature and humidity measurements, they seem relatively reliable, not very accurate but at least the trends are correct.

UPDATE: Now 3 out of the 4 have broken (or 4 out of 5, if you consider that one had already been replaced). Don't waste your money.

Unfortunately, after a few months, problems started with disconnections and battery exhaustion. In total, I bought 6 and 3 of them have gone offline, and with mathematical precision, I see the other 3 also going offline in a few days. It's a shame because I really like Sonoff, as well as its ewelink application

For now, it works great and provides measurements every 5 minutes. It has been seamlessly connected to SmartThings.

I bought 2 for testing, I have them placed as far away as possible from the bridge, 10 meters with 2 rooms in between, one and the other in the bathroom, 8 meters and one room in between.
For two days now that I have been monitoring them, they work perfectly. If they continue like this, I will also buy the remaining 4 that I need.
I will come back with an update.

I bought it 6 months ago and I can't say that I am satisfied.
+ The good thing is that the measurements are relatively close to reality (compared to an analog and digital thermometer).
But...
- Very limited range, if it moves more than 5 meters away from the zigbee hub, it loses signal and when the battery is more than 2 meters away from half, it doesn't connect, nor is there any button for reconnection...! The only solution (besides reset) is to remove and insert the battery, although it doesn't always work...
- Also, the Sonoff application is very limited and to have all the capabilities, you have to become a subscriber, something that is free with other manufacturers.
For the above reasons, I do not recommend it, and generally not Sonoff, as with a little more money you can buy better devices with many more automation capabilities without a subscription and more reliable.

I created a network of four devices and they work flawlessly without any disconnections. Another excellent product from Sonoff. They are compatible with Alexa and can be used in scenarios. They consume minimal energy due to the Zigbee protocol.

Although I have been a fan of Sonoff for years with several switches, I have been completely disappointed by the Zggbee series.
Constant disconnections of the temperature sensor and the door contact (even though they are within 5 meters from the Sonoff Hub pro and I have reconnected them three times in the four days that I have had it).
Try another brand for Zigbee protocols.

Reliable temperature and humidity sensor. It only works through the Sonoff ZBBridge device and not directly connected to the app. There are no disconnections and it can participate in multiple scenarios with other Sonoff smart devices.

I bought 2 last week but I can't say that my experience is very good... They go offline several times, resulting in the only way to restore them is to reset them! This means that if scenes have been created, they will have to be recreated from scratch because they lose the devices.

Update 16/11/22
Stay away! Completely unreliable temperature. Although a fan of Sonoff, this particular device disappointed me

I have purchased a total of 3, one for each room of the house, and I am very satisfied. It has temperature and humidity display. The next step is to automatically control electrical devices in combination with POWR2.
Update: I have integrated them with Home Assistant and they work perfectly so far. You can turn on electrical devices based on the temperature or control them through a thermostat via HA

I have purchased 4 together with the ZigBee Bridge and I had no issues. In fact, one of the sensors is located outside the house in an adjacent storage room.

Unfortunately, they no longer come with a battery (CR2450)

It did not satisfy me at all compared to all the other products from the same company that I have.
Measurement deviations or zero readings, disconnections, and it did not cooperate easily with the company's Gateway as well.
(possibly defective, will be checked)

Cute sensor, combined with aeotec's SmartThings hub. However, its functionality is somewhat strange, as it sends measurements approximately every half an hour and in the meantime it appears offline, as if it goes into sleep mode - so it may not be suitable for someone who wants more immediate/frequent measurements. Also, the measurements are probably not 100% accurate, but the deviation is small, around 0.5-1 degree.

Simple and reliable at an excellent price. I haven't noticed any difference in measurements compared to the Aqara equivalent.

The sensor works in connection with Sonoff's zigbee usb stick as a coordinator with zigbee2mqtt in Home Assistant. I have been using it flawlessly for about a month now and it seems to have good accuracy compared to other thermometers I have. It is also very small and discreet. Overall, very impressed.

It works perfectly for a month now, with automation turning on a socket for a heater according to the temperature. Note that it requires the bridge

It connected immediately and provides accurate temperature and humidity compared to others I have at home. The Sonoff bridge is required for it to work. Its battery lasts a very long time.

It shows a temperature 0.5 degrees Celsius higher than a conventional thermometer.

You can use it as a trigger in scenes on eWelink.
Alexa does NOT see it as a trigger.

Edit after 2 months... it constantly disconnects!!
I do not recommend it (even though I am a fan of Sonoff).