To those saying the MP is 'more or less' a M6... couldn't disagree, and agree more...
Leica has a history of making minor changes, that make major differences in their body versions (the one exception being the M5). The 'up-grades/changes/variations' between and within the models of M3, M2, and M4 were minor apart the viewfinder magnification change M3 vs M2/M4. Leica 'purists' did go a bit crazy with the plastic advance tip and front body controls of the M4, but in use they made little real difference. The double stroke to single stoke advance, quick load feature, and angled rewind were major, but looking back not deal breakers. (and I don't want to get into the M5, which Leica engineers let all the stops out on)
When the M6 came out I sold my chrome M4 with the happy thought of an M4 with a built in meter. But in many minor ways (which added together) it was not an M4 ( finder! its more than just a condenser lens that was left out, self-timer, zinc, engravings, steel gears, body covering... fit and finish ) - a bit of a disappointment. Yes, a good camera that did the job and I used for close to 2 decades, it just didn't have that 'classic' Leica 'feel' for me.
An then the MP... its 'back to the past' and my original thoughts of what I'd hoped for that M6. Maybe the best way to put it is - its a refined M6 - everything is made and designed better, from the viewfinder, meter, shutter, brass and engravings, smooth action of the shutter release and advance, and even the retro parts don't seem out of place, fit and finish look to be a step or two in the 'refined' direction with CNC machining of parts (getting closer to my M4 ;-)
If you are wondering which is the better camera, for all those that say the M6 is the same, given the choice between the two without thought of condition, an M6 being 20+ years old and in need of repair/CLA, cost differences... would anyone really pick an M6?
As a camera to use, and the end of the manual M-series film camera line its just about perfection in evolution Leica design style.