We read some comparison between Cleen and other apps. To clarify: we tried to simplify the photo rating from different origin. Cleen is a spin-off of the rating function of our @tapsbook product, an iPad app we started in 2013. The main interest of Cleen is to help user pick the favorite photos (and delete bad ones at the same time).
Our research has shown that, normal consumers tend to be conservative when delete photos, on average people think only 23% of their photos are trash, so just weeding out 23% of trash photos is far from a good utility. For the non-trash photos, there is almost 50-50 chance the photo is just average rather than a favorite photo. That is why our focus is primarily help user spot those top notch photos - these photos are the ones we probably will share or do more with.
@TheJoWo If you long hold a image you will see every inch of the details in full frame - all this is optimized for one finger operation. Seems we have done a good job hiding this zoom in feature :)
Toymail
Practo
Tapsbook 
Clean Clode
Emoji Kitty