With the default Photos app, you can easily slideshow your collection of photos, with options for transition effects and music.
But even before you unlock your device, you can turn your iPad into a digital photo frame—just tap the "Picture Frame" icon (see the screenshot) and enjoy.
Can you show each photo faster or slower? Yes. Open the app Settings, select "Picture Frame" on the left panel, then on the right panel, select a time interval you need. You can also choose a transition effect, select zoom, shuffle and albums.