Genjok2010 I have been using Windows Phone for 5 years, I believe that I can fully judge the system.
Of the maps there are only built-in from Microsoft (based on Here, almost useless in Russia), there are Yandex.Maps, they are superbly made and are very convenient in themselves.
The browser is only built-in more or less adequate, but it is terribly artifact about scrolling. There are UC and Opera.
For organizing there is a built-in Outlook. It copes well with its task.
Or is it better to say which of the really necessary programs that are on Android, is not on WinPhone?
I can tell you for sure, there is not a single program with equal analog functionality on Android. We take any application, absolutely any, that is on Android and WM, and the application for WM will have less functionality. Perhaps the only exception is VKontakte. In it, all the chips appear before other platforms, but it is believed that VKontakte uses the client for WM to test new features, because the smallest audience. Let me get back to the point, even Microsoft’s Android applications have more functionality. A trivial example, OneNote.
IMHO, Microsoft needs Windows 10 Mobile only for a tick, they say, a complete ecosystem. Do not mess with this platform. I didn’t mess with her after my first phone on WP stopped supporting a year later, but the price for 1320 was really pretty and there were no analogues in screen quality. And now again. In September, Skype will not work on WP8.1, and up to 10 I can not and do not want to upgrade. And I'm pretty sure that Microsoft will soon abandon the mobile division.
Sorry for too much too much.