I was lucky enough to be given a Lumia 900 by Nokia and I have to admit, I do like the device and I do like the Windows Phone UI - but there are a significant number of problems which need to be addressed.
Firstly, early adopters of the Windows Phone platform have been hung out to dry by Microsoft - 1st generation devices will not be issued with an upgrade to Windows Phone 8, which when you consider those who purchased these devices (as opposed to carrier subsidised devices) paid upwards of £450 for the Lumia 900 and slightly less for the 800, to then be told 8 months later that they will not receive an update for the new version of the Operating System, is very disappointing. Early adopters cannot be blamed for being very angry at Microsoft for this - there should at least be some form of reasonable trade-in available so early adopters can recover some of the costs whilst still making an upgrade to Windows Phone 8, especially in light of the announcement by Microsoft that Windows Phone 8 will be officially supported for a minimum of 18 months (which just rubs even more salt in the wounds of the early adopters left with Windows Phone 7 devices).
Now to the serious issues with the OS which to my knowledge have still not been addressed in Windows Phone 8.
Network Time Protocol (NTP)
Many Windows Phone 7 devices (particularly Nokia Lumias) suffer from time loss issues. My Lumia 900 for example, loses several minutes every month, which is incredibly annoying and makes syncing up meetings and conference calls with my Calendar less that satisfactory as I will generally be late if I do so. There is no way to sync Windows Phone 7 (and as far as I know Windows Phone 8) with a network time server - such a simple fix to implement, but never addressed by Microsoft.
Password Protected Office Files
It is nice to have Office on my phone, but it is useless if I cannot open password protected Office documents. Given the inclusion of SkyDrive with Windows Phone, it seems to be incomprehensible that Windows Phone does not support opening password protected Office files because anyone who is storing files in the Cloud (SkyDrive) without encryption or password protection, is a fool - especially if said files are business related.
I understand that some of the encryption woes have been addressed in Windows Phone 8 but as far as I know there is no way to fully encrypt the userspace with either version 7 or version 8 of the Operating System - this leaves your contacts, calendar, SMS, email, social network messages and notifications etc. all unprotected - something I take issue with.
Virtual Private Network (VPN)
Windows Phone 7 (and as far as I am aware, Windows Phone 8) has no means of connecting to a VPN. In the current world where telco's are using Deep Packet Inspection (DPI) to sniff everything you do on their network for the purpose of ToS enforcement or Behavioural Profiling/Advertising, the ability to encrypt all your communications is not just a feature, it is essential - especially on a device used for business communications. The DPI use is not limited to mobile networks either, the vast majority of free WiFi services across the world are employing the same sniffing technology to inject behavioural ads into the content you view via their networks - that means your emails, the web pages you visit, your online chats or any other Internet Protocol (IP) communication which is not encrypted is being spied on by countless third parties.
Every single app I have installed on Windows Phone requires me to consent to Location Tracking (literally every single app - it is almost as though it is a default) even though I have disabled location tracking in the OS. This is a massive privacy issue and one which as a privacy professional, makes me particularly angry. There is no excuse for it, just stop doing it. If you develop Windows Phone Apps stop asking for permission to things you do not need - the vast majority of apps do not need location tracking and if your ad partner requires location tell them to either provide an option without location tracking, or find another ad partner. If you refuse to grant location tracking on these apps, they will not install - it is wholly unacceptable.
So, just a few reasons why I am at odds with Windows Phone - all important, all serious and all indications that the platform simply is not yet ready - especially for business use. That said, neither are Android or iOS which both have their own very serious security and privacy issues - does this mean the only option is RIM? I have never used or reviewed a Blackberry so I honestly can't comment - although I do have a dozen or so friends who work for RIM and swear by them - what do you guys think (answers in comments)?