Okay, first impressions…
It looks cool, it is a little bigger than the eee900 and looks a little less kiddish. On the other hand, it’s a magnet for fingerprints and smudges.
Boot time is great at about 20 seconds (less?). It uses a customized Fedora with a ‘locked down’ XFCE on it. Well, not so locked down, but you have to realize you can only get at the ‘good stuff’ by using Alt+F2 (run command) and then launch your best friend xterm. From this command line you see&feel that you’re in a regular Linux again.
The screen is very pretty with good viewing angles and nice contrast. However it’s hard to read under direct light. Wouldn’t fare well in the sun I think. The spreaker are crap did not try headphones yet but it should be better. The webcam is crap indeed but it’s still kind of cool to see it actually working… I managed to take a bad picture of myself. 
Keyboard is really great, in fact I’ve got a small keyboard at my desktop PC to conserve space and the One’s keyboard is actually much easier to type on. The touchpad is very small which is kind of annoying, plus it’s sensitive so sometimes you’ll touch it by accident and your mouse cursor will go flying… definitely use a small mouse if you can. The laptop also gets a little bit hot after 2 hours of usage (I was using adapter) and moderately hot after 4 hours of continued usage. You still won’t burn your lap or fingers then though.
Getting online was really easy… networkmanager scanned for wireless networks, found mine and even found another one in the neighbourhood. Somehow LiveUpdate seemed a little slow… or maybe they were just big updates. After I figured out how to launch Pirut from Terminal, downloading and installation from there went pretty smooth. LiveUpdate gave me a lot of updates though and it’s nice to see Acer making an effort to support the system well. Oh, and they actually like Yahoo a lot since the integrated ‘web search’ launches Yahoo from Firefox even when Google is set as default in FF itself. Also, homepage for Firefox is something like acer.yahoo.co.uk … ‘custom Yahoo portal for Acer customers’. Whatever.
The interface is actually pretty nice, very intuitive and something I think most people would be able to use pretty quickly. Acer also makes liberal use of links to folders: almost every application is set to save in a particular folder: Firefox saves in Downloads, the webcam/photo application saves in Photos (or was it Pictures?), … A couple of acer’s own applications for video and photo/slideshow are included but they are really very basic and limited. There is also mplayer but unfortunately it lacks a number of useful codecs. I did not yet try how mp3 playback fares, but I expect that to work.
In general, everything is pretty snappy & fast even with 512mb RAM. Even OpenOffice (2.3) loads in 3-4 seconds. Ironically, Firefox at first laucnh can take longer… aside from OOO and Firefox, there’s also mail/contacts/calendar (I think it’s Mozilla Suite they use, actually), note-taking application (basic, why not Tomboy I wonder), file manager (basic but nice and does the job… I suppose that’s Thunar) and a number of games including e.g. Frozen Bubble and Supertux. Kind of awkward and funny is that acer include one game of their own which you have to pay for the full version… the logic behind that beats me.
Typing is easy, the screen is very nice and everything is fast&responsive, even with a number of programs open simultaneously. I also put in an extra 16GB HCSD card for extra storage. Still have to see how the laptop fares on battery power alone, but my very first experience was a pretty positive one.
) would be the best fit for me, since I intend to use it as a more-than-capable (and a bit larger) PDA.