Not having seen a Surface myself I have no idea if it's true, but most reviews I've read seem to agree that while the lower res *is* noticeable, the screen has other qualities (low glare, high brightness, great viewing angles and ClearType) that mostly make up for it.
I actually am disappointed by the 1366x768 res, I currently use a Galaxy Tab 2 10.1, with a res of 1280x800, it's a nice enough display, but when comparing it to the iPad3 the difference is massively noticeable, browsing photos on the 'retina' display is honestly a real pleasure, the only reason I didn't buy the iPad was because I prefer the open nature of Android, but the iPads display did seriously tempt me.
I also think a higher res display is more important on a tablet because you're generally going to be holding it a lot closer than you might perhaps with a laptop, etc. I do think this is pretty short sighted by Microsoft, the next Nexus tablet is rumoured to be a 10" tab with a (iPad beating) 2560x1600 display, so it pretty much looks like this is the way it's going for this type of device...Unless you're Microsoft, that is.
I'm puzzled by the seemingly differing reports on the performance of the UI, hoever: some reviewers claim that it runs butter-smooth, while others are suposedly experienceing quite a bit of sluggishnes.
I might seriousy consider this if I can find one on the cheap. With a Danish keyboard, that is.