When comparing Gwenview vs Eye of Gnome (eog), the Slant community recommends Eye of Gnome (eog) for most people. In the question“What are the best FOSS image viewers for UNIX-like systems?” Eye of Gnome (eog) is ranked 9th while Gwenview is ranked 11th.
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Pros
Pro Easy to navigate folders
Pro Quickly view image metadata
Pro Easily resize, crop, flip and rotate
Pro Keyboard shortcuts can be redefined
Pro Images can be sorted by name, date and size
Pro More lightweight than other kde or gnome dependent applications like gwenview, gthumb or kphotoalbum
Pro Double-click to view Fullscreen
By default, double-clicking on the current image opens it in Fullscreen mode. This can be turned off in Preferences if desired
Pro Image Slideshow
You can view a slideshow of all images in the current folder, and adjust the delay between images in the Preferences dialog
Pro ESC key exits Fullscreen and program
Pressing the ESC key exits Fullscreen mode, as well as exits the program ... hence press the ESC key twice and you're out
Pro Can set image as wallpaper
You can set the current image as your desktop wallpaper directly from within this program
Cons
Con Has a bug that causes certain png files to show brighter than normal
The image, if is a png that contains gamma information, will appear washed out. There is still an open ticket concerning this issue.
Con Very slow on remote folders
Compared to others, like XNview, is VERY slow when retrieving images from shared folders (NFS or Samba).
Con Not lightweight
Needs a lot of KDE packages.
Con No APNG support
And it won't be it seems https://bugzilla.gnome.org/show_bug.cgi?id=151281