My ten free sample Flickr MiniCards turned up from moo.com today. Here's what they look like, along with the little dispenser the samples came in and one of my current business cards for scale.
The material the cards are made out of is very well chosen. It's a nice heavy card stock, pretty much matt on the printed side and with a nice soft sheen on the image side. Definitely not gloss, though, which I was a little worried it might be.
The text side of the card — which I think of as equivalent to a standard business card — is just large enough for a few lines of contact details, and that looks great in the format. My flickr avatar image works quite well at this scale, although I'd drop the flickr logo when buying some of these for real.
I'm not blown away by the results I got, though. There are two problems, both at my end.
The first problem is the shape of the cards; few of the images I've uploaded to flickr look really good at this very wide (2.5:1) aspect ratio. I can see myself occasionally shooting specifically for this format in future.
The other problem is that a lot of my flickr images end up pretty dingy in this medium (the two you can see here are the best results, and they're not nearly as punchy as they are on screen). If you're going to try this product, make sure you have lots of contrast and colour or you might be disappointed: what looks good on the screen isn't necessarily going to look great on a card.