Nik Fletcher nails it in his latest blog post:
“Yes, it’s an entirely prescriptive way of computing - one that the hackers, tinkerers and geeks will find alien and protest about its lack of openness. But here’s the thing: for the people who the iPad is aimed at it really doesn’t matter that this experience is prescriptive - and the more you look at the decisions Apple seem to have made in building the software on the device, the more you realise that the iPad is perhaps the first high-technology product ready for - and entirely aimed at - a mainstream audience right from the get-go.”