Make up your mind, is it good for a dev eloper, or good for the end user? It can't be both on the same level. Knowing various .NET/CLI caveats, I'll take a guess - WP7 is better for the user, and you are saying that it's made with the user in mind, and here is what I have a problem with... How come something is created with the user in mind, yet it tries to lock in the user and milk cash from him/her whenever it can? Doesn't that seem rather contradictory? Let me put my user hat for a moment, and lets say I purchase a WP7 device - how am I to transfer my music library from my Linux laptop to it? And even VBox is not a solution, already tried it and it didn't work, but even if it would - why would I buy a desktop OS to run it in a virtual machine just so I could transfer my files to my mobile device? How is that 'with user in mind'? How is it bad for the user to be able to access the device via a standard USB connection, or to transfer his/her files from network storage, or...? Name me one good reason to only be able to access your device through a proprietary app and how can that be good for the user? I personaly have no problems with closed-source apps/OSes/whatever, I have a problem with locked in systems directed and censored by some outside entity - in such system you end up leasing your device instead of owning it, where the manufacturer can change the terms of use retroactively, after you've purchased the given device - and I just cannot accept that. True, given a choice I prefer OSS, but closed source is just fine as long as it uses widely accepted standards and does not lock you in.