Nothing is quite like the feeling of having a brand new piece of technology in your hands. I got my new smartphone four days ago, and have been playing around in Nokia Lumia 920's Windows Phone UI for the last few days. It's a unique experience, and I feel like a kid on Christmas Day. The phone is responsive and has a lot of useful features. And it doesn't hurt that it looks good as well.
I've already found tens of useful apps on Microsofts App Market, all free so far, and I've tested a lot of the phones features. Despite Windows Phone's lesser popularity and consequent smaller app market I haven't yet missed any applications from m previous Android phone. Quite the opposite I've found some of Nokias free and included apps very useful. Nokia's maps and GPS services in particular is superior to almost all other similar apps for mobile phones. They're all you're going to need if you use GPS on your phone. If you need a better GPS than that you'll have to buy a dedicated GPS device.
I'm really liking Microsoft's UI with tiles. On Windows Phone it works brilliantly. And it looks way better than iOS's and Android's icons and widgets.
Unfortunately I'm still waiting for a micro-SIM which my operator was supposed to send to me so I can use the phone as a phone. Right now it's just a tiny tablet without SMS or calling capabilities (except through Skype an Viber). The micro-SIM has taken longer to arrive than I was promised and I'm getting impatient.