I have tested Nokia Photo browser with my Nokia N95 8GB
It is great idea at all .
1)It is a new experience to Nokia Devices ,you can see more image thumbnails in this app and choose one to see.
2)it is smooth to browse and open ,rotate
3)Face detection is a good idea ,you can choose this options in few photos ,where you have group of people and browse face by face,but improvement needed .
4) Zooming experience is great as you can use short cut keys(#,*)
The area still need improvements
1)Slow to create thumbnails for the first time to all existing images and every time to newly taken images.(if you took a photo and try to see from photo browser ,it will take some time )
2)Auto rotate some times gets stuck in thumbnail view and photo view both.
3)I have a detailed review with the image illustrations in my blog at http://pspezone.com/vblog/noki