I'm 16 days in, and for the most part, I'm still enjoying the Nokia Lumia 900.  Reception and battery life continue to be good, and the phone can definitely take a beating thanks to the polycarbonate shell.  But I've found the "multitasking" features to be pretty useless.  All too often, I'll be composing a text message, and have to stop to check a calendar event or something of that nature.  When I come back to the message, the text in the box is gone - or so it seems.  You CAN return to it by hitting the back button several times (or by holding the back button), though I find that to be counterintuitive, particularly for those of us that are constantly flipping back and forth between things.