I don't love the keyword, but it will be fine for a site like this. Make sure you market it only to the countries that apprechiate .co.uk [Surprisingly, the UK] as the US will never bit onto this foreign extension. You might also lost traffic to the .com.
IMO it is exactly the opposite of what you intend to do - I presume you want visitors to rate the members photos. At first glance your domain may mean that you'll rate the photos.