Of course one of the most successful keyboards of all time, and still used in many studios and by many artists. I would also like to know how many are still surviving from more than quarter of a million sold.
I would advise anyone to get one while they are still a reasonable buy, I got mine for less than £100 and I can see the value of them going up as more go to the synth graveyard and they become rare.
You can get software to download patches ( via MIDI ) very cheap and of course thousands of patches are available, also makes a nice weighted key MIDI keyboard.
Here is a simple tune I made using the M1.

