I recently bought an MX and mint M-50/f1.7 to replace my Spotmatic SP F which was dyeing a slow death... I've also used a MF Minolta SLR and several 35mm rangefinders but generally my film experience isn't great so keep that in mind
Anyway, the legendary MX:
Body: SMALL!!! Aesthetically quite similar to the Spotmatic and all other K and M series bodies, but very, very little. This may or may not be a good thing. It’s compact enough to be a ‘pocketable SLR’ (big pocket, small lens) but some people complain that it’s too small for large hands. I find that it feels more secure in the hand (compared to Spotmatic) due to the significantly lighter weight… Personal preference I suppose. An MX Winder will probably make it more comfortable if you do have problems. Build quality is outstanding.
Controls: This is a fully manual camera. Ie. it is fully operable without batteries (light meter obviously won’t work). But this also means it doesn’t have aperture or shutter priority. So if this is your thing best go for an ME Super or similar. Other than that it has all the bits you need, including some nice little details like the red dot showing when film has been advanced and the combined DoF Preview lever and self-timer. Everything has a nice, tactile feel to it, although the shutter dial is usually a bit stiff. Doesn’t ‘officially’ have mirror lock-up, but there is a well publicised DIY trick that works on most bodies. Centre-weighted metering only, which is accurate and fast, although some complain about the lack of spot-metering.
Viewfinder: Wonderful

Significantly better than the Spotmatic and Minolta SLR’s I’ve used, and absolutely incredible if you’re used to an APS dSLR. Big and bright with a handy combined split-prism/micro-prism focusing screen. Shutter speed and aperture value are both displayed, although aperture may not be displayed properly with some non-M series lenses (my Chinon 45mm lights up the focus scale instead). Exposure is displayed as a series of LED’s, which is not to everyone’s taste… I personally prefer the Spotmatic’s needle.
Generally: I love this camera, easily the favourite in my collection. Great to complement a dSLR system, when you just want to take it back to basics and enjoy photography. The size makes it an excellent, unobtrusive street camera. Build quality and reliability are outstanding, although there are a lot of light seals that will need replacing at some point. Worth mentioning that I’ve only ever used the MX with smaller lenses; K24/f2.8, M50/f1.7, M135/f3.5 and M200/f4, and while it feels well balanced with these, if you use larger lenses frequently you may be better off with a K series body… Overall, this is my go-to camera and strongly recommended . 9/10 marked down only for stiff shutter dial and LED light-meter. Get one while they're cheap
Pentax MX and M50/f1.7 'kit lens'. Fully manual without batteries.