Here's a few more....mine is listed at 3MP 'Interpolated' which is actually 2.1MP. I'm sure the newer ones are much better...but if you do get an older one be sure it has both the 1M and infinity focusing stops. Mine has no preview lcd, but hell, if you're really worried about your shots bring your real M3! My battery has lasted for over 2 years, but I haven't used it much, maybe 150-200 shots.
The digital ones are 'chubby' at the back (as said in a previous post), but still really tiny. I believe the film ones (8mm) are more like the real M3 in all aspects of size (to scale). All the M3 controls are just for show, but the film advance lever (and even the self-timer lever!) has a spring, so you can pretend you're actually winding film.....those Minox guys sure have a sense of humour!
You don't get much for a yard and a half nowadays....and if the new ones are 4 or 5 MP then they'll not just be curiosities but take great shots as well.