Miui update isnt fast to begin with. Poco f3 only receive update once every 2 months. That u call fast? Samsung is already catching up on the software update speed and even oppo/realme, which i saw find x5 pro is already on april update on the demo phone, and also realme gt 2 pro is on march update at least
I did mention before, it is the matter of personal preference. I dont like miui overall, in terms of how the entire OS looks, how settings are being categorized. And even unlocking bootloader requires to wait for 1 week, which i dont get it why when we purchased the phone, it is our own rights whether to unlock.
Kua zhang? The overall looks of the software determines the overall user experience of the phone. It might not be important to some, but it is important to me at least. MIUI looks just like china looking OS sad to say, same looks as oppo/oneplus/reame too frankly speaking. U can have top of the line specs, but if software is bad, it makes the phone looks bad, spoiling the overall experience of the phone..
I did use miui for at least 2 to 3 days on poco f3 honestly speaking, i can leave with it definitely or even any normal users can live with it... But i returned to custom roms after that