The advantage is just 35 instrucion to learn.
The disadvantage is just 35 instructions to use.

The PIC18 series is much better, and pin compatible. more stack, less memory banks. ( people who use 8052's can not complain about ohter CPUs having too many memory spaces.

You would have a better time if you used C.
As far as bits SETB and CLRB should do bits.

As far as the interupts. You check the interupt enable bit and the interupt flag for each interupt source. Note that not all interupts clear with the flag, you have to clear the reason too. Or, it will just retrigger.
The single interupt can make latency slow. You have to put the important ones up front.

There are many quirks. But it gets low end jobs done well.
Someone described them as a bunch of peripherals with the minimum amount of CPU to connect them together.

Do not forget to check the eratta sheet. Some Parts have serious bugs.