Yes, I have a 65 mm Mir, the later Mir-38 version, and this one is quite OK.
Here's a list of all my P-6-mount lenses:
45mm Mir: totally sucks, very soft, uneven plane of focus (one corner is even less sharp than the other unsharp ones), very flare-prone - stay away from this one.
45mm Hartblei shift-lens: based on the 45mm Mir optically, bnut with better mount and quality control; still suffers a bit from unsharpness in the corners, you have to stop down at least to f/11 to f/16 to make it work; also, with 6x6 format, only about 6mm of shifting is possible befor the lens will start to vignette.
50mm Flektogon (black MC version): great results, very good; a huge & heavy beast though, filters are hard to find & expensive.
65mm Mir-38: quite OK, not as good as the Flek, but not bad either; from experiences with friends who own the same ones I know that there is quite a bit of sample variation with this one.
80mm Biometar (zebra version): quite good, not very sharp wide-open, but get's very good by around f/4 to f/5.6; nice bokeh. A bit flare prone (it is only single-coated).
80mm Volna: sharper wide-open than the BM, but with ugly, distracting bokeh. Otherwise quite good.
120mm Biometar (zebra SC version): quite good, nice bokeh, more manageable as a portrait lens on the road than the Sonnar.
180mm Sonnar (late-model black MC version): The best bokeh ever! Makes marvellous portraits. Rather low contrast; already sharp wide-open, but in a pleasant, not too harsh way; a bit flare prone. Also, you have to open up about 1/2 a stop if using it at closest distance; the special 10mm extension ring from CZJ is very useful for filling the frame in head-shots (though this ring won't mount on my K60).. A huge and heavy beast, esp. with the lens shade mounted it looks like you are using a bazooka.
250mm Telear: Good, sharp, not very fast, but that makes it quite small; handy tele lens for hiking; bokeh is not great, but not especially bad either.
2x Arsat converter: quite OK as far as converters go.
Roman