I have a iiic.
Having separate focusing finder and viewfinder is both a pro and a con. Pro is that the focusing finder has built-in diopter correction and is magnified, allowing augmented focusing accuracy. Con is that it is separate from viewfinder and makes it difficult to get shots of randomly moving objects (children). As with anything, with practice, the above mentioned con will probably get better.
I know with the iiic there is also an issue with the film sometimes slipping down on the take-up spool and your exposures might partially end up on the sprocket holes, but I haven't had that problem and I don't know if it was fixed on the iiid or not.
Anyways, good little tank of a camera. Classic. Shutter is VERY quiet. Needs a CLA every 10 years or so for all those tiny mechanical parts and the shutter curtain may need to be replaced as well (rubberized cloth, eventually starts deteriorating) but otherwise will outlast you and your grandchildren, probably.
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