It's my birthday today and my wife bought me a new pair of Shimano XT SPDs for my fixie.
Up to now I've been riding with the pedals off my old Ribble, but they've suffered a bit with a couple of crashes that have left them a little bruised, as you can see below. Unfortunately I fitted the new pedals before taking a snapshot for comparison, but let it be said they look lovely and shiny (until the first ride in the rain).
The argument for and against SPDs versus road pedals is not worth it: at the sharp end if your pace is above evens — faster than 32kph or 20mph — then road pedals will make an incremental difference to pace. However, walking around shops buying food at 3am in road shoes can be dangerous in wet weather, and SPD-type shoes win hands-down every time you have to walk anywhere at all really.
I use SPDs on both road bikes now — my fixie and my old Ribble — as well as the Brompton, although the Brompton's pedals have a noticeable amount of play in the axle, but they were still good for 6000km last year!
UPDATE 10 January 2016
I rode out with CTC today with these pedals. As it happened, the SPD shoes were brilliant when I had to literally run across a field and a small wood to fetch a lady's husband after she'd fallen off her bike and face-planted just down the road. It wouldn't've been fun to do so in road shoes!