Without wishing to do a dis-service to OCUK, I wouldn't touch a laptop that wasn't from a big name manufacturer. I've seen the difference in build quality between companies like Rock and Dell/HP over time and particularly for an ultraportable (going to get thrown around a lot, spend half the day being carried around in a bag etc) I'd take the big names any time.
Samsung are almost in that league for build quality, they're not too bad at all, my dislike stems purely from the slightly plasticy machines (they look great, until you get up close) and not being terribly impressed with spec vs. weight.
I agree about the 12" screen, it makes a difference over the 13.3 in terms of how easy it is to carry round. I disagree about the weight though, I went from a Sony SZ to a Dell D430 as my work laptop, thats 13.3" 1.7KG to 12.1" 1.1KG, the difference was huge, partly down to the screen size but I think the weight matters too. In my opinion the 1.7KG bracket is pointless, either go really light and get a sub 1.3KG ultraportable or get a 2KG 14.1" machine.