My employer just issued me a Windows 8 phone - a Lumia 820. As a Nexus 4 owner, and previous iPhone 3/3GS/4 owner, here are a few thoughts on the Lumia 820:
Battery life is very good - better than the Nexus 4, but is that because I'm not inclined to fiddle with it? No, I actually think it is very good.
No LastPass or Remember The Milk apps. Deal breaker. Voice recognition is there, I'm told, but it's not obvious where.
Connecting to Bluetooth in my Renault Megane RS 250 was easy, and it asked me if I wanted to download my address book (in principle, better than the Nexus). I said "yes" but it just didn't.
Sometimes the in-built audio player starts playing. It's not clear why, but there is no indication which audio player is playing, and you have to manually start each audio app to find out what's going on. Yesterday I was in a meeting and my colleague's phone started playing Pandora for no reason. Deal breaker.
In-built GPS navigation: this is sensational. Not only does it come with the phone, but the maps are downloadable for pretty much anywhere in the world I am likely to ever drive. That's worth the cost of the phone! Don't buy TomTom apps - just get a Lumia phone. It will be cheaper if you need to drive through Australia and two other countries.
Ecosystem: it's ok, but just ok. Evernote, TuneIn, Audible, Facebook, LinkedIn, Pandora, Spotify, Skype, Tripview, YouTube are all there. But, there are a few things missing - I really like the control over audio I get on the Nexus with Persist. I'm a paid-up Tasker user too. I miss these.
Verdict: As a work phone, I can live with it. Having said that, it doesn't look up the Active Directory contact list automatically - that's another step. Why??? There are so many little missing pieces that should link this phone to the Microsoft ecosystem at work, and it's not obvious why they're missing. Maybe it's just a bit of time needed. If was a brand new smart phone user today, I'd go:
1. Nexus 4(5) - average camera
2. iPhone 5S - great camera
3. (by a very wide margin) Windows Phone 8. No good reason to buy this phone.