I have the Lumia 920 and Microsoft absolutely nailed the design of the OS. It works seamlessly with Office Live/Online/365 whatever the heck they call it too. The home screen of the phone agitates my OCD something fierce because I have to get it just right or... I'll... die...
Seriously though, its a great phone and if you need one for work like I do, might as well get one you really like.
Lumia 900 owner here. OS is nice, but the apps... just as an example, I got really frustrated with IE this morning because it didn't recognize StartCom as a trusted certificate authority, and it doesn't cache my response (to ignore the warning and browse the page anyway). The https page loaded the first time, but subsequent pages just showed blank screens. And that stupid SSL warning page just kept popping up.
It's 2013 and I can't browse certain web pages with my expensive smartphone...
Seriously though, its a great phone and if you need one for work like I do, might as well get one you really like.