Same stuff to watch out for. Sticky aperture, jammed winder, fungus or fogging of the lens, micro-scratches on the lens, light leak etc. Bigger concern will be the repair costs. I was about to purchase a Canon QL17 until I found out that overhauling the darn thing could costs as much as SGD250, when the cost of a minty one on eBay costs only SGD100. I can't imagine how much it will cost to overhaul the rollei. Another thing to consider is that the production methods of older glass is inferior to current day methods. As much as it is a Zeiss glass, I doubt that it will measure up against modern zeiss glass. One benefit I can think of is the lack of mirror slapping, as such, you should theoretically get sharper pictures. If this is gonna cost you a few hundred dollars, you might be better off considering a used Minilux, T3 of even GR1V.