Like anything there are positive's and negatives. The effect on...

Like anything there are positive's and negatives. The effect on net exports you point to is the main positive. But when you look at the USD think about it as purchasing power. Yes their stock market has rallied like everyone else's, but their dollar has fallen. So if the stock market goes up 40% but their dollar collapses against a basket of currencies by (lets just say for arguments sake) 40%, then the purchasing power of the wealth they are creating on the stock market is actually a net neutral, and considering the destruction of wealth that occurred in 2008 this is a very bad thing for owners of USD denominated assets. What's worse is that printing money and weakening your dollar will eventually feed back in to the real economy (for example by importing inflation), which might necessitate a rise in interest rates in to a weak economy, causing stagflation (simultaneous low growth and high inflation), which would cause the stock market to fall again, and then you have falling real wealth and falling value of that wealth relative to everyone else. Not a good look. But on the upside the AUD gets a little stronger and we are tied to China and Asia now (America is now 5th on the biggest buyer of our exports list). But really a weak US is bad for everyone, maybe just a little better for us than most.