The Dell Venue Pro may not be the most popular Windows Phone. In fact, it probably isn't; it was the last WP7 device that Microsoft updated to Mango. But since it was indeed last, that means Microsoft's roll out of Mango has been completed.
That's a good story in itself, but what's even more important is that the entire process took a comparatively short two months. Keep in mind that this is with many different devices from many different manufacturers.
On top of that, this was only Microsoft's first major Windows Phone 7 update. I'm sure that whatever's coming next from the company will be even smoother than this. Microsoft will undoubtedly gain more loyal customers because of its fast and smooth updating process. Every phone got Mango within two months; I can think of at least another operating system that isn't managing to get all its phones to the latest software ever.
Of course, I hate to see that happen to Microsoft's competition, so I hope that this news will get Google and its partners to ramp up software updates.[Windows Blog]