exec sum: slow. wireless antenna is relatively poor.
I have borrowed a Toshiba NB200 netbook for my recent trip to Germany. My conclusions based upon a few solid days of conference use:
battery life: 6 hours.
size, weight: fairly good.
screen: a little too reflective, but quite good.
keyboard: fine once I got used to it.
performance: terribly slow.
Trying to do anything that's not web based is reasonably painful. I don't know if this is the case with all netbooks, but it's still too slow for my use. Two IM programs, a word processor, firefox, tweetdeck running on Ubuntu netbook edition taxed the poor little thing.
update: I would have written this earlier, but the wireless dropped out. Wifi: horrid. Connecting to public hotspots is extremely difficult. I even had problems in my bedroom, 6 metres or so away from my access point. Not a good selling point for a 'netbook'.