Yeah, some 20 million devices sold was the last time I've read and somewhat about that 50.000 number of apps in there. The thing with puzzle based games seems right on spot, I've personally seen a couple of folks who do not play games whatsoever but bought several different puzzles in the past few months. Price and easy way to get them and those 15 minutes breaks or long train rides is what makes this group of people jump into it as well.
On 'related' news, seems like ZX emu might be released soon, heheh.