My ebook device for the past few years has been an hp ipaq 4700 running at vga resolution. As far as pda's go this was the nicest and sharpest display you could find for ebooks. The iLiad just blows it away in sharpness. It's hard to really describe without seeing it in person, but it is much better. The eye strain is also much lower since you don't have a backlight to contend with.
Unfortunately mine arrived with a battery that won't charge so it is going back for repair tomorrow, but I'm frantically working to get all my content converted over to the right pdf size and I'm looking forward to catching up once it's returned.