If america do it properly then HSR will be great, but there are huge factors to consider, one of them being the huge amount of initial infrastructure to set up, and also the fact that the trains would be travelling faster than the human eye/hand reflex can cope with.
i.e Before the train driver even has time to see the truck broken down on the crossing ahead, he has hit it. Boom 1000+ people dead.
So you need to have the infrastructure and safety mechanisms in place for 100s and 100s of miles across rural land. To maintain that amount of track and keep a high safety record you need to spend a lot of money which by all accounts america doesn't have a huge amount of. (Although I propped the economy up with my hard earned $$$ on a little trip to colorado back in February, so you can be thankful for that!) We have the same issue in the UK - to set up a HSR network costs a silly amount of money.
BTW I FUCKING LOVE TRAINS!