I'm wondering how this download only will play out. At 4G there will be quite a few people that will not be able do it, or it will just seem too cumbersome. Apple seems to think everybody should have a big pipe I guess.
For example people with low end DSL connections that are typically around 256-512kbp/s, it will take 20-40 hours at full speed.
Here's a handy site to help calculate how long.
Got mine via 10mbs cable. It took a while (~45 minutes to an hour) - about 1 1/2 - 2 hours total for everything to complete and boot up. I like this delivery method - near instant gratification.
Not sure if I like the new, gray, 2D scroll bars though.