I'm currently using a four-year-old Xiaomi 10U smartphone with the Penumonic OS, which has been notoriously unfriendly to old devices. The OS is plagued with bugs, and the developers seem to take ages to fix them. The experience has been frustrating, and I'm starting to lose patience with Xiaomi. The slow performance, frequent crashes, and poor battery life have made me question whether it's worth sticking with the brand.