I buy these in the size I typically purchase shoes in.  My feet run slightly wide and flat, so take that into consideration when looking at whether to size down and how much.  They fit a little loose, but that's honestly how I like them.  Once they break in, they feel less loose and more like they are the appropriate size.  First day I wore them they dug into my Achilles a bit, but after that they have been fine.  Even after a whole night of dancing.

Style-wise, I can't imagine a more versatile shoe.  They are, in my mind, equivalent to the black and white Chuck Taylors, but for adult outfits.  These will look beautiful with denim, cords, khakis, and just about anything else that's not formal.  And they look better as they age as long as you care for them.

The only thing I would change on these is perhaps some sturdier laces, maybe a set of waxed ones.

Every adult male should have a pair of these.