That's a tough call, and you'll probably get conflicting advice, even from vets. My cat Brrrruce had an immune system disorder (IMHA) and my vets recommended that he not be vaccinated against anything (even rabies).
I have a compromised immune system, and I keep getting mixed signals from medical people. I was advised against getting my Hepatitis B shot that I should have for work. When I told the clinic I was behind on my tetanus vaccination, the nurse said she didn't see why I couldn't get it, and so I did.
I think the main problem is that a vaccine may not be effective if the immune system doesn't react to it, so it would be a waste of time. On the other hand, I would steer clear of any vaccine that is live or modified live. There's a danger of contracting the disease from the vaccine if the immune system can't fight the vaccine.
I know I'm taking a chance, but my cats don't get vaccinated against anything but rabies anymore (except Brrrruce). I fear immune system disorders and vaccine-associated sarcomas more than the diseases themselves.
As for rabies, the only reason I get the cats their shots is because the public health system gets uppity about it. Fact is that there has never been a case of rabies reported in any animal that has had at least two rabies vaccines in its lifetime!
Before you criticize someone, you should walk a mile in his shoes. That way, when you criticize him, you're a mile away and you have his shoes.