besides price which is always a consideration, there are other points as well:
a. framelines are different. The CL has a permanent 40mm shown, regardless of whether u use the 50mm or 90mm (in addition to the respective framelines). To most, this is okay, I find it very irritating.
b. There are only 3 framelines, 40, 50 and 90mm. The popular 35mm frameline does not exist but the 40mm lens is quite excellent, whether it is the Summicron-C or the M-Rokker. Portraits lens on the CL would be the 90mm unless attach an external viewfinder.
c. The size is small, but so is the finder magnification of 0.6, compared to the M4-P's 0.72x.
d. The sound of the shutter isn't as silky smooth as compared to the other Ms. Isn't really an issue but if you have tried the Leica M-bodies, the difference is very real.
e. The exposure meter will die eventually. The repairs are costly and usually not worth the $$$. I usually use Sunny-16 or I use an handheld meter.
Having spelt out the issues, I will say that I like the CL very much. It works best with the 40mm or with an ultrawide lens like the Cosina Voigtlander 15/4.5 or the 25/4 lens with an external viewfinder. I also use the Collapsible 50/f1.9 canon lens on the CL with no problems too.
The Leica CL is one of those bodies where I have bought and sold about four times, i currently own 2, both bought 2nd hand for under 300 usd each. (the 2nd body was 500 usd with the 40mm lens thrown in).
raytoei