Had a Nokia 930 - loved it on WP8.1, the live tiles are something completely unique and exceptionally useful and make the UI more personalised than any other smartphone, think of the homescreen as a page full of your own post it notes, simply brilliant, the people hub area is also a nice simply easy way to pull all your facebook, twitter etc...updates together, but not unique as Blinkfeed on the HTC devices does this equally as well.
Apps....now the apps although most of the general ones are there, I would say apart from a couple that are as good if not better, most of the quality is far behind that of the iOS and Android versions of the same thing, if you like social gaming forget it, zynga have only a few poorly produced games, yes Asphalt 8 is great, but still only runs a medium graphics detail on the flagship L930.
My advice to Microsoft = Stop faffing about and get your app store sorted, WP8.1 is spot on as a UI, but is let down by its app support and this is the reason I have returned to Android.
EDIT: But why do I constantly miss my Nokia 930 ? if WP could directly install .apk apps from Android now that would be the perfect smartphone and i would never look back, please tell me this maybe possible one day