The Nokia Lumia 920 has a much better camera than the SGIII to be sure, and also a better touch screen as well. You can even use it with gloves! However, it lacks micro SD expansion, and also a mini HDMI out-port. Also, while WP8 is inherently more secure than Android, the ecosystem currently has a much smaller number of available apps.
In my opinion, the Lumia 920 competes well against both the SGIII and the iPhone 5, and my guess is that the WP8 ecosystem will end up gaining new market share rapidly over the next few years...
It's not selling great (yet) because there haven't been enough of them to sell. My local AT&T rep, the "WP Expert", said so far reception of WP8 is very positive. Much better than WP7 and the Lumia 900. But before we can say the 920 is selling well we have to see more supply hit the market.
it is lumia and what do you mean selling great. You have no numbers to support that. We need to hear how many were available to determine if selling great. If they sold 1 million that is unimpressive. They need to sell much more for the stock to move.