I have successfully used the 16C550 in an 8052 application, connected via the external bus (P0, P2, ...). It is a low cost, yet powerful chip. If you don't need the embedded FIFOs, you can use it as if it were its venerable ancestor, the 8250.
Some possible drawbacks when interfacing to an 8051 MCU: 40 pins chip (a lot of PCB area); interrupt request pin active at high level; the clock oscillator external circuit might need some trimming to guarantee it oscillates.

Regards,
Alfredo del Rio.