It must have been a real relief when they found Daniel's father was a match, otherwise it would be terrible having to be on the waiting list.
As for Daniel getting the vaccine, that makes sense because when you have received an organ transplant, your immune system will recognise the organ as a foreign body and reject it. To prevent that, transplant patients like Daniel have to take drugs to suppress the immune system. But if you're taking something to suppress your immune system to prevent organ rejection, the obvious side effect is that you're going to be more vulnerable to infections. It's definitely a good idea for Daniel to get the vaccine. The down side is that he is going to be on these immunosuppressing drugs his whole life, so this is not going to be a one-off thing. This problem will always be there.
As for the rest of the royal family, I think it makes sense for them to get the vaccine. Bear in mind that their job involves a lot of handshaking with members of the public. It's impossible for the security folks to keep the infected people away from them. How could they possibly screen EVERYONE? There's just no way to know when the king might shake hands with someone who has just touched a contaminated doorknob.
Most of the negative reports I've read about the H1N1 vaccine are not all that surprising - even with regular vaccines, there are always people who get a bad reaction. As a matter of fact, this is true for ANY medicine, whether it's a herbal health supplement, or a cold medicine you get from the supermarket, or a flu jab. The only difference is, H1N1 is big news, and every possible bad reaction to the vaccine (even the ones that are later shown to be unrelated to the flu jab) gets reported in the news.