After a few hours playing with the M10(P) I'm on the whole impressed - it's a very well thought out piece of kit and the controls and display are a pleasure to use.
Some minor quibbles - I'm very surprised that there's no margin reset button nor peak hold setting - both margins and peaks reset automatically after about one second. There should be a menu option to set the peak hold time, with infinite hold provided for, and with the record button acting as a reset button (it currently has no function once you are recording).
The auto level feature is actually a preset level (about '3' on the knob) and it appears to turn on the limiter. So that's good insofar as there's no pumping of background noise - when things are quiet it doesn't raise the level, it simply rapidly limits any peaks. But as the preset level is somewhat conservative, if you are recording something quiet you're going to have to up the level in post production.
The backlight can be turned on (for the preset length of time) simply by pushing down the power button. However, don't do that for too long else it will happily switch off during recording. They should have required one to deliberately press "stop", then turn off.
If replaying, and you stop or pause for more than 10 minutes, the M10 will go to sleep but then wake up at the exact point you left it. Once turned off, it comes back on at the start of the last played track.
If you put nested folders into the recorder from your PC, it "flattens" them into a single list of all folders (which is fine by me).
Transfer speed seems a bit on the slow side but I might try optimising it for speed rather than for quick removal, in Windows. [Edit - tried that and it seemed to make no difference. Transferring mp3 tracks to the recorder runs at about 3.5MB/s, from the recorder at 5MB/s]
And those built in mics... there's no getting away from the fact that stereo imaging is poor. I'm not quite sure what Sony had in mind when they specified the mics. Sound quality is good and low noise, but the imaging would preclude doing anything much with the recording. Sound pickup is much the same whether you talk (or play) towards the display face or the front edge, or even from the rear. This means that it's very forgiving about which way you point it, but unless the sound source is very close, stereo separation is rather limited, and you are likely to pick up a lot of what you don't want (eg room acoustic or audience round you). Personally I'd be more likely to make serious use of a Zoom H2 built in mic recording.
The "P" model has a dead kitten windscreen and a carrying bag included, but otherwise I think it's identical to the normal version. Colour is matte dark grey, close to black.
All in all, a very sexy and pro-looking piece of kit, which will probably take the place of my RH-1 Hi-MD recorder (and others) unless I particularly need the tiny size of that one.