I think the best answer is to try it yourself. Of course, dual core is obviously better than a single core. But the way the OS optimize the CPU capability is much more crucial. Yes, Android & Apple (just ) have a dual core system now. Those Gingerbread OS from Android only really shine on those dual core system but on single core? Its still a bit laggy. When people pitch iPhone 4 vs Galaxy S2, its still a single core system but it feels really smooth. Windows Phone 7.5 feels so smooth and at some area better than the iPhone ( in terms of smootheness ). On the Lumia 800, it is quite strange that both Nokia/Microsoft didnt add those front facing camera since its already clear, Skype is owned by Microsoft and coming to WP7 really soon. The N9 also have those.The NFC stuff is not that crucial,yet....