To me it feels a little bit confined and shows a lack of confidence in your work to shotgun EVERYTHING on the card, especially since it's such an eclectic mix of photos he has to choose from. I'm also wary of the stacked box look in general. But that would be a way to go one sided. The best looking business cards are focused, though. I do split cards 50/50 if I have to, but my natural instinct is to use both sides.
Good photography shouldn't need a lot of design to sell itself. If anything it gets in the way of the photo itself. Also don't used a serifed font if the rest of your site is sans-serif. Keep it consistent.

