The photos app was amazing. Live tiles are amazing. The music player and it's live tile was amazing. The performance was the same whether on a low end budget phone or the top of the line model.
So many good ui and ux decisions like the lack of hamburger menus and placement of all menu items along the bottom of the screen with the extra items being hidden away in a drop-down using ellipsis. System wide light and dark themes jazzed up using an accent color that all of your apps respected.
The People hub (contacts app) was the central point for all social media. Facebook and Twitter were integrated. I didn't need fb messenger. Skype and fb messenger were integrated with the messaging app.
Damn, I wish we made it.