I had been looking at smartwatches for quite some time. The Youtube reviews were barely tell you the day to day use. There are a number of them available on Aliexpress, Amazon and others listed through Panda Check.
This was my experience:
You can install apps from the Google Play store, however the display is too small for most. My favourite, Endomondo was useless as the the screen was just a banner with the app title.
Bluetooth audio and GPS - 2 hours battery life
Tether to phone via Bluetooth, no GPS or pedometer - 8 hours
The heart rate monitor was unpredictable - I couldn't trust it. I am a darker skinned, but it shouldn't be that off when taking measurements. Besides, a regular watch and taking my pulse is straightforward.
The antenna for GSM/WCDMA/3G, Bluetooth and WI-FI were in the bracelet making it difficult to change the bracelet. I could not imagine making a phone call with the watch even though it was possible.
When listening to audio, the Bluetooth would cut out all the time. Listening to a lecture of 30 minutes would be very frustrating.
The watch, which is to be used as a standalone phone, did not sync my SMS, e-mail or other notifications with my smartphone.
Changing faces, was an elaborate process, that I couldn't care about given that the battery life was so short.
Aside from an alternative to a smartphone when tracking running or other sportive activities(of short duration), I do not recommend getting an MTK6580 smartwatch.
ps. I sent it back to the seller. Apparently it never made it, or the seller tells me that's the case. I lost about $100 in the process.
