Just bought one of these for my father who's aging PC is starting to suffer. I've been quite impressed so far. Went for the Linux based one as only £149 with 1GB and 160GB HD, but have immediately installed Ubuntu Linux (9.1 Karmic Koala) instead. - the installed Linux is a bit pants.
The Atom 230 processor uses hyperthreading, so appears as two cores to Ubuntu. I installed an extra 2GB RAM in addition to the 1GB it came with - not sure how necessary that will be. Getting the case open was a pain, but there are YouTube videos to show you how to do it. (and it probably invalidates the guarantee). Probably best to use some sort of plastic blade rather than a flat screwdriver as you can scratch the case quite easily!
The Ubuntu install went completely without a hitch - it found the wireless h/w without any problems. I needed to run the Hardware Drivers menu option to get it to install the Nvidia drivers, and the final result looks pretty good! Using the Nvidia drivers reduced the load on the processor considerably when doing anything graphicy.For example, the System monitor CPU load reduced from 15% to 4% or less.
Haven't tried the HDMI out yet - might be worth a go on our 1080P telly just to see how good it is. Also untried is the audio.
The thing itself is tiny, I bought a USB DVDRW drive to go with it (it has no optical drive), and the drive is bigger than the Revo! Using the drive made installing the new OS very easy, but you can also install from a USB stick, so getting the drive isn't vital.
Quite impressed so far. Will report back on my fathers experiences as he starts to use it!
I also bought a new PC at the same time - a cheap Acer Linux desktop (Athlon 215x2, 4GB RAM, 1TB disk, DVDRW, GeForce 9200, £289)- as my ancient Athlon XP2000 has finally given up the ghost. Power supply failed and appears to have taken the mobo with it. New PC came with a dodgy version of Linux, so installed Ubuntu on this too. Again, very pleased with the result so far. Appears considerably faster than the old one!