He's been vehemently against Nokia's decision to leverage their smartphone strategy on Windows Phone. For more awesome reading explaining why, check
this out.
As explained in the link above, it's not Nokia's decision to use Windows Phone on their smartphones that is the chief problem. They are, essentially, hedging
their entire existence on the platform, which is a very bad bet for a company whose popularity has always been stronger in Europe, Asia and developing nations. It's almost like a Kodak in reverse in that they are, more or less, giving less importance to their bread and butter and more importance to a huge, HUGE risk. (Notice that HTC and Samsung, the top dogs in the non-iPhone smartphone world, use more of their resources for building Android and
their own OS's than Windows Phone.)
The sole fact that, to this day and despite a very recent system update, Windows Phones
still have the crippling text-message-of-death bug clearly demonstrates where Microsoft thinks they're at with the OS. I haven't seen any of the major players on Android/iOS commit serious time to Windows Phone yet; until this happens, it's a sinking ship.