I think you're right that those first few minutes (seconds even?) matter a lot, as far as mass market appeal and sales go. This is what the iPhone excels at. Especially when it first came out. People had never seen anything like flick of the finger kinetic scrolling before and it blew their minds. Steve Jobs said as much at the conference where he introduced the device; all he had to do was show people the scrolling and they were sold.

That said, I think there's also a downside to this kind of appeal. It plays to the lowest common denominator. The iPhone is slick and easy to pick up and full of eye candy. But it's also a very limited device (no multi-tasking, Big Brother watching over the app store, very slow to provide obvious features like flash support, MMS, and cut and paste, limited user ability to customize the device). Apple tends to favor, I think, the appearance of user friendliness over actual long term usability. OS X is the same. It looks nice and friendly and inviting, in an almost childish way, but using it (at least for me) sucks. Keyboard commands are not very systematic across the whole platform, the file browser is the worst most overly simplistic of all file browsers, the whole concept that the program must be quit separately from closing the window is ridiculous (my parents pretty much always have every program they've ever opened running on their iMac, grinding it to a halt, until I visit and close some, because there is absolutely zero that is intuitive for them about the idea that closing the window does not quit the program).

I think you have to balance a platform that is inviting and appealing right off the bat, with gently pushing people into a little bit of a learning curve, so they can have a better long term experience. People aren't idiots and they will learn, if you make the process for them gentle and not too annoying. I feel good about what I've seen in Maemo 5 so far. Maybe the potential of the design won't be fully realized until Maemo 6. But I feel Nokia and Gnome are heading in a good direction.