I use them as my "round town" shorts, or any time I don't fancy getting lycra'd-up for a ride in the country (stops me feeling too much of a twonk in the pub at my mid-ride rehydration stop
).
They're nice and comfy (a little bit of stretch helps here), albeit a tad warm at times (usually paired with Polaris padded undies). They're also quite water-resistant, but I wouldn't like to ride far in the rain wearing them - they were fine for 28 miles on Islay in August, but much further and I think they'd have been getting a bit clingy.
Oh, and I wear them fixed or geared - the Rapha Fashion Police haven't caught up with me yet...