Here is a post from Teach42 commenting on the iPad as a choice for 1:1. In general, the evaluation is very positive with the caveat that better is yet to come (apps). I agree.
I have listened to concerns raised by others (e.g., DarinKing on Twitter) and think that the issues may be different for K12 and Higher Ed. The issue Darin raises concerns the task of getting apps on the machine and how this is accomplished – e.g., delivery of apps through the app store rather than locally, connecting the iPad to a computer at the outset. I can see this situation as challenging in the K12 setting. In higher ed, the student is given much greater responsibility. Buy the textbook if you want – we don’t pass them out in class.