To all who, in this thread, downplayed the advantages that accrue to the wealthy: I hope you noticed the Supreme Court's significant decision in Citizens United v. Federal Election Commission, which will further the ability of money to influence politics in the USA.
This isn't going to be as drastic a change as many think since money & connections have been buying politicians forever but now it'll just be a little cheaper and easier for them. Less hoops to jump through. A much more efficient corrupting.
Back to the insurance issue I just read an interesting opinion that the penalty for not buying in is going to have to be much, much higher than they are proposing (~$750/yr) to offset the cost of people only getting insurance when they need it.
Remember, the only way lower-risk people are going to buy insurance is if it's very cheap and even then it's generally going to be only catastrophic-type coverage with a large deductable. This new plan, since anyone can get insurance at any time (akin to getting fire insurance as your house is burning) very few, if any, lower risk people will want to pay any premiums and they'll just wait until something happens and the risk pool won't be able to be spread properly among people who are higher risk and lower, causing the premiums received to fall incredibly short of the payouts.
This plan will bankrupt itself so quickly it's not funny. Then the govt will come back and change the rules of the game on us and jack up the penalties for not participating to $3-5,000 annually. We can't say no then as a large segment of the poulation will have become dependent on the system.
This plan is easy to balance out on paper but there are many real-world realities that will cause its bankruptcy. Prices will go up, fraud will go up, people will seek care more often, lower-risk people won't buy in at all, etc.