Not amazing sound, but very cheap and portable (and has a handy belt clip).
It takes 9V batteries (reviews and QA responses imply that one is included) but will also work with a power supply (not included).
I've had my eye on it for a while but haven't seen it come below £21.99 so this seems like a decent price (though as the MS-2 has never been posted on here before, I don't really have a point of reference).
Modes - Clean & Overdrive
Controls - Volume, Tone, Gain (on/off)
Power - 1 Watt RMS
Loudspeaker - 1x 4" Speaker
Battery powered - Yes
EDIT: and now it's gone down from £20.30 to £20.00