Current rating system looks a bit weird. 6 stars, really?
My suggestions are:
1) to display 5 stars instead of 6 (loose 0 rating, UI patters, if I rate it 0 I as well might just don't rate it at all)
2) When rating is assigned it should show it on stars not as a number (4.83)
For example, 4 1/2 stars highlighted.
How complicated to make it happened? When should we expect to see this feature.
I think most of the code is written, just need to make few tweaks to make it perfect.
Piwigo is awesome! Keep up a good work! =)