The "growth" in the private sector as you like to refer to it, is simply ramping up credit leveraging.
Unsustainable, it will crash again, better question is will there be enough credit to go around for the next 6 months to convince America Obama fixed anything.
The truth doesn't matter anymore, people just want to see some positive trajectory and worry about the consequences later.
That is a good question, but whether or not it crashes depends on whether or not the economy takes off and really improves. If it does, those companies which ramped up early stand to benefit. If it does not, those same companies may well crash.
The length of a recession does not make a good metric to measure its severity in my opinion, simply because bungling the response will artificially prolong it and give credit to the very people who bungled it. As I see it, there are three different factors. First, having taken a dip, the economy will always automatically recover if left to its own devices, constrained only by the permanent effects (if any) of the recession's causes. Second, there are factors (such as outsourcing our manufacturing) that make it more difficult to recover from a recession than in the past, especially through consumer demand & spending. Third, there are those factors that Congress and the President introduce, intentionally and unintentionally, which will boost or retard the recovery. The first two seem to me to be of greatest magnitude, leaving us to argue over the relative importance (and direction) of Congress' and the President's contributions.
That said, I'm not at all impressed by most of President Obama's and the Democrats' contributions, nor of Bush's and the Republicans' contributions. I think TARP was a good idea that was badly implemented, perhaps partially necessarily because the scope of the damage exceeded the available remedy. I think the GM bailout was a good idea with the exception of Obama using his office to break existing law to screw the bond holders and give the company to the autoworkers' union. Other than that I don't think either side has an idea that will do much more good than damage. Obama however receives a lot of the credit for the recovery and a lot of the blame for its weakness simply because of his office, not because of what he has done or not done. McCain has as little free market experience and knowledge as does Obama, so I see no reason to assume he would have done materially better.