The most common criticism is that there is the possibility of an undetectable inflation bug. There has in fact been a inflation bug in monero, but it was not exploited and patched.

Regarding the possibility of an undetectable inflation bug, it is my understanding that the part of the code that would have to have a bug is very well understood and very closely watched / studied.

If you use monero as a medium of exchange and not a store of value, this is less of a concern imo. Just like I withdraw some cash from my bank to make private purchases you could swap some bitcoin for monero for private payments.

There have been inflation bugs in bitcoin also of course, the latest being in 2018 which was also patched before it was exploited. In 2010 somebody printed 184 billion bitcoin due to a bug and the chain had to be rolled back.