I suppose if I were to mention a concern, it would be that America seems to have, at least from impressions given, a bit of an addiction to treatment. The reason things like the NHS work is because there are a lot of people in the UK who don't feel the need to take medication for every single ailment, whereas America, at least from impressions, is far more inclined towards chemical treatments for things like depression, over-activeness and a host of other psychological orders that could, with all respect, probably be dealt with far more efficiently without the use of chemicals.
Secondly, I don't know if Doctors get subsidies from pharmaceutical giants for prescribing their particular drugs, but it's worth checking out. I can see that problem being far worse in the US, especially at first. Doctors need to be encouraged away from prescribing Medicine for everything and start considering cheaper, but equally effective treatment, else the toll on the system is going to be quite substantial.
Right now, in the UK, there's a move to 'Use it when you need it' with the NHS, in other words, booking an appointment in the Doctors for a cold is not a profitable use of the Doctors' time, and causes delays for people who do need the Doctor. This is something else I can see being a concern at first.