Many fans seem to be disappointed by the number of the tracks. But I think it is a good thing to have "only" ten tracks.
Today everything goes so fast that people don't even have time to appreciate the moment. So back in the 80s I remember when I had listened for the first time the THRILLER album on a cassette. It was so exciting to read all the songs and to discover them carefully one by one. It was like discovering a delicious meal with a starter, main course and desert. People used to take time to appreciate the songs. The fact that there were only ten songs, forced people to listen to them carefully. In any case more carefully than when there are more songs.
When BAD came out, there were also only ten songs. I just can't explain with words what a wonderful feeling was to discover the songs one by one. Rewind the cassette (which also used to take a certain time), re-listen to the song, paying attention to all the little details.
Today we want quantity and forget quality, and when we are not happy with the first notes we just skip 'cuz we know there's quantity (and also because we have become impatient). Yes we were carrying heavy walkmans with only ten songs compared today with ipods and mp3 players, but damn, instead of having 3000 songs that can't be lisitened correctly in one day, we were plainly enjoying the good old stereo of the few songs the albums had to offer.
As far as the new album is concerned, I have a theory. I might be completely wrong, but I wonder if some songs were not supposed to be sung at the THIS IS IT tour and that have been kept until now to be released on this new album with an accompanying video of unreleased THIS IS IT scenes which are actually rehearsals of those new songs. It's just a guess, but it would be pity if there were no scenes of rehearsals of the new songs.