I tried a lot of slideshow programs for Linux and this is why I'm disappointed.
I recently wanted to present a bunch of fotos to my friends and family but the pictures were from many people, so they were ordered neither by date nor by name. This seems to pose gigantic problems to all normal, simple slideshow programs.
I manage my pictures with Shotwell, which can only show the images in the order they are displayed in the program, so I couldn't use that. Feh can display a list of images, but I'd have to create the list manually, which doesn't work with pictures named "SANY0305.JPG"...
So I ended up looking at other options: DVD slideshow generators. They claim to generate a video file with animated still pictures, usually with a nice appealing Ken Burns effect (which I very much like). There's lots of them, and PhotoFilmStrip is what I theoretically would like, but it doesn't render 100% correctly (some images are offset far enough to expose a black border) and rendering takes ages on my netbook.
All the other tools are either several years out of commission or are so horribly complex and unintuitive that you really can't use them for more than 2 still images. ffDiaporama for example claims to have support for the Ken Burns effect, but even after half an hour of googling, watching a French YouTube tutorial and another half hour of aimlessly monkey-testing the UI and exploring all possible dialogs I couldn't get a single picture to display a Ken Burns effect. Any decent UI engineer would drop dead upon seeing that monster of a GUI.
So I conclude: There's no easy to use tool for Linux to create a slideshow of images, certainly not one that doesn't have to render a video file and supports Ken Burns effects.