Thank You Cards - A good idea?

I have recently designed some Thank You cards for a friend. They are a little different from my usual designs as I also inserted a photograph to make them even more personal. These are a couple of templates of the design. You can see that there is a space in the middle where a photograph would go. I have added a couple of photographs of my two beautiful daughters in the purple one just to give you an idea of what they might look like. Obviously, the customer would send me the photograph(s) they want included. The back of the card is designed like a post card, with a space for a message and lines for a name and address. You can simply fill it in, stick on a stamp and post them as they are.  They are not available on my website yet as I am seeking some feedback first.

What do you think? A good idea?

http://thebeaskneesandthecatswhiskers.co.uk/