I found a link on Twitter to a review of the Streak, Dell's 4.8" Android tablet. The Streak is more of a smartphone than a tablet so I wasn't planning to cover it in depth.
This reviewer has made a number of interesting remarks on screen size and usability. Yes, it's only his opinion, but I think it's worth a read:
But… the Streak is really rather good too, though you won’t be able to use it in full sun, as you can with e-ink. My everyday phone is another Android gadget, the HTC Desire. It runs pretty much the same stuff as the Dell but has a 3.7 inch screen. The difference that extra 1.3 inches makes is quite remarkable. I can’t read anything of length seriously on the HTC. On the Dell it’s no problem at all. Oh, and one nice surprise. All the apps I bought for my Desire download automatically to the Streak too – they’re tied to my Google account, not the machine. A neat touch.
The Desire’s screen is too small for serious book-reading for me. On the Streak it looks like this which is much more like it (sorry but taking pictures of this screen is not easy). Now a bunch of seven-inch Android tablets are on the way – Samsung will supposedly have one out next month, and by Christmas there will be five and seven and ten inch Android tablets everywhere. But actually it’s really quite usable on the five-inch.
This guy is going in my RSS Feeds.