Main features:

* Premium mobile OS (high minimum hardware requirements)
* Clean, uncluttered interface with distinctive design language
* Easy and thumbable user interface
* Smooth operation with cool animations and transition effects
* A fresh start with no legacy support needed
* Backed up and developed by one of the largest software companies in the world
* Excellent MS Office mobile implementation
* Top-notch social integration
* Excellent cloud services integration (SkyDrive, Windows Live, Xbox Live)

Main disadvantages:

* No system-wide file manager
* No videocalling
* Limited third-party apps
* No Bluetooth file transfers
* No USB mass storage mode
* No memory card support
* No multitasking
* No copy paste
* Too dependent on Zune software for computer file management and syncing
* No music player equalisers
* No Flash or Silverlight support in the web browser
* No sign of free Bing maps Navigation so far
* No DivX/XviD video support

As you can see there’s more disadvantages and it looks like Micro$oft following Apple’s way : as much restriction as possible….