Based on my experiences with my wife-as-student I have to say the Sony's screen is too small for many, if not most, text books. I've reflowed several for her but she wants the pictures/tables/diagrams to all line up with the text so "(see diagram on left)" makes sense. She also wants to be able to flip to page 251 when the teacher announces that page number for discussion, which is a teensy bit awkward when her text book is reflowed.
We went to see a UMPC: too small, feels like a brick, too short on the battery life.
The iLiad takes too long to turn on/off (especially with no suspend feature), is too delicate, is too awkward/expensive/unpredictable/takes too long to be repaired and it's screen is too small as well.
She hates dragging the "heavy" Motion LE1600 to class but it's lighter than her books and she positively loves One Note 2007. For my part I like that it is durable, rapidly repairable in-country and I can keep a battery charged, for her when she forgets to plug it in to recharge.
She spends more time reading her CONNECT ebooks on the LE1600 than on the Sony Portable Reader. She professes to like the Sony Reader but I think she says that because I got it for her for Christmas. What she really seems to like is being able to buy and download ebooks.