I've been a Venus booster for a long time, precisely because of the 'cons' you mention above (along with the temperature, which you don't mention).  Mars has very little atmosphere, which makes it almost as challenging as the moon to colonize.  Venus' rich atmosphere is *a resource* - vital for industrial purposes, and unavailable on Mars.

Interesting thing about Sulphur Dioxide:  the deep sea vent ecosystems thrive on it.  It's the basis for chemosynthetic ecosystems on Earth that live under the kinds of pressures Venus' atmosphere creates.  The volcanic vents also are much hotter than people can tolerate, though nothing like 800 degrees.  

That heat is also a resource.  Chemical reactions are stimulated.  Metals become malleable.  IR (heat) can be used to generate solar power.  None of that on Mars.  

Given the resources Venus provides to colonizing industry, it's a much more attractive target economically, despite that it seems unwelcoming.  Since Earth life already uses Sulphur Dioxide to found food chains, creating novel life forms adapted to Venus specific conditions might well be possible.  Carbon Dioxide is also the essential feed stock for photosynthetic ecosystems, such as we are part of, and Venus has that in spades.

But, all that isn't really why I want to colonize Venus.

It was really the cloud cities that sold me on Venus, not the valuable resources necessary for industry =)