They almost got it perfect - the zoom feature is a nice add to the 600 it really makes pdf's (graphic based pdf's) usable on the 600 - You can just use your finger and drag the screen around (fairly peppy seems to keep up nicely) The only thing i would change is the have big scroll arrows on the scrren which burn a lot of real estate and are superfulous due to the ability to simply drag the page around - at least an option to turn them off would be great!
ps the 600 contrast is in my book about halfway between the 700 and 505 - a manageable tradeoff for the added touch features. pdf zoom etc
http://www.youtube.com/watch?v=oKpl4wiG-Bs