All crypto is difficult to get right unless you're a crypto expert. RSA is not unusual in this regard.
The thing that is unusual about RSA is how many people /kind of/ understand it. Crypto people who dislike RSA say that this leads to a proliferation of terrible RSA implementations, and that it is therefore more dangerous to use than eg ECC. Crypto people who like RSA say that its relative accessibility makes it a more popular target, and that in the absence of a catastrophic break the more-studied cryptosystem should be assumed to be more secure.
Personally I've spent some time recently with badly implemented ECC, and I don't think the mistakes being made there are fundamentally different from or rarer than the mistakes you see in poorly implemented RSA.
The thing that is unusual about RSA is how many people /kind of/ understand it. Crypto people who dislike RSA say that this leads to a proliferation of terrible RSA implementations, and that it is therefore more dangerous to use than eg ECC. Crypto people who like RSA say that its relative accessibility makes it a more popular target, and that in the absence of a catastrophic break the more-studied cryptosystem should be assumed to be more secure.
Personally I've spent some time recently with badly implemented ECC, and I don't think the mistakes being made there are fundamentally different from or rarer than the mistakes you see in poorly implemented RSA.