"And you can't really _do_ anything with iPhone, like upload music to it (I don't have Windows or Mac OS), or use Debian on it... So it depends of quite a lot of things."
I would say that about 99.99% of people who have bought an iPhone are perfectly capable of uploading music in to it, so claiming that "you can't upload music in to it" is wrong. I don't have an iPhone, but I do have an iPod touch, and I have zero issues with uploading music in to it.
I can understand the dislike for the iPhone if you use a computer that is not supported. But IIRC, at least Amarok-devels are working on supporting iPhone/so that particular problem could also be fixed.
"The openness has delivered the tangible benefit that there are no restrictions on how the user is allowed to use the device."
And then people would look that does it have something like cover-flow (no), can you remote-control your media-center with it (no), can you use the device as a mouse (no).... and then they start to wonder that what benefits has that openness brought to the table so far. And most phones out there, even closed-source ones, do not place limitations on the user. So it's not like that lack of restrictions is a unique featre that only Openmoko has.