Hi, I'm a recent Photoshop convert.
I'm generally a very happy chap but I am sorely missing the ability to:
alt [ (or) alt ] to quickly move up and down from layer to layer.
example, In Photoshop, if there are several layers and layer 1 is visible, alt ] selects the next layer and makes it visible, while deselecting and hiding the previous one.
Yes, I can alt-click the thumbnail in Photo to do similar (which is a great feature), but the keyboard shortcut is a valuable tool, particularly if you need to a/b/c edits or if animating something.
alt click a layers checkbox to show/hide all layers