Hey,
I'll have to play with one to see what the charm is. I couldn't imagine ever using one in a studio environment where you have access to a mouse, keyboard and 19" monitor, you absolutely cannot beat the power of a computer and software.
What I can imagine doing with such a machine is going out and gigging with it live, I'm sure it's a lot more stable than a computer as it was designed in theory from the ground up to be rock solid. I'm sure also that it's MIDI timing is rock solid, you don't have to compete with conflicting drivers and hardware issues that you have with computers.
It just seems so limiting to be forced to have immediate access to only 16 notes instead of a proper keyboard that has the ability to transmit a high resolution of velocity and aftertouch, and it's not intuitive for playing musical notes. Also, it only has a simple LCD that looks no bigger than the displays on modern calculators! Waveform editing must be a LOT of fun with that screen...
What would appeal more to power users (I think) would be getting one of the newer Z series samplers (the blue and silver ones) and the 16-pad controller in tandem with a computer and MIDI sequencer like Cubase (or Sonar, Logic, etc.), although you wouldn't be able to bring it on an airplane or record the engine sounds from your new car from it... : )
I think that so many hits were written on it because it was the gear that the producers had at the time, they could have easily written those tracks using a computer, sampler and keyboard...hits are made with producers and talent, not with hardware!
The MPC doesn't have anything in it sonically better than their S series samplers module brothers. However, the physical properties of the device may have lent to the development of different genres of music, hip hop and early techno being two of them. Now techno music is very elaborate and complex, it would be difficult to sequence a modern track using only an MPC, yet it sounds like modern hip hop still relies on them exclusively.
A friend of mine is planning on getting the MPC2000xl or 4000 (if he can afford it), I can't wait to play with it!
Nick