I've got a Kohjinsha on order from Conics for a friend of mine, and we've done quite a bit of research on it. Interesting fact - the Raon Vega, Kohjinsha, and Pepperpad 3 all run the same basic hardware platform (Geode LX800 processor + chipset, 800x480 screens.) The chipset handles video and most IO.
This gives us a lot more info to go on.
1) Linux Compatibility - Excellent. The pepperpad 3 is linux.
2) Performance - I think it was around a PII-300 for integer performance.
3) Video - 2D only, and they mean it. No DirectX/3D support, period. They apparently couldn't get iTunes to run on the Vega because of it.
4) Movies - Excellent. Apparently the Pepperpad is used for video quite extensively. I also found a review of the Vega that said Divx up to 2 megabit worked flawlessly. Supposedly there is video acceleration function in the supporting chipset. The painfully machine-translated review (which gave me "bad HK-subtitle" flashbacks) said there was a problem playing DVDs (I think). I suspect that's got more to do with the drive & interface. I bet that loading a DVD image directly on the the HD and playing the files from there would work perfectly.
5) Battery life - Supposedly excellent (5hrs?) LED backlight + super low power CPU should hopefully translate into decent power savings.
The guy who's going to be using it has a 860 and a 3000, but he seems a bit jealous of my Libretto He's going to be using it for eBooks, web surfing, game emulation, and watching movies.
(Also, he's got a nasty sense of humour. Someone he knows bought laptops for his daughters - two girls ~5 foot and 100lbs if you're lucky. The father is a hefty guy over 6ft tall. He bought them a pair of 12lb desktop replacement laptops without thinking much of it. These girls list to one side if they try and take the things anywhere Anyway, my friend thinks that showing off the Kohjinsha to bug these girls is an "added benefit" Yes, he's single and likely to remain that way...)