I have a few suggestions to make it easier and quicker to crop more than 1 image quickly:
Access the crop tool in browser mode.
Currently you'd have to enter viewer mode first, and then hit Shift+C. Why not allow the crop tool in browser mode? I was searching high and low where this elusive crop tool is, only to find that I arbitrarily have to be in a different mode that I seldom use.
While crop tool is visible, drag a rectangle to crop.
Currently you can only enter numeric values manually, this is not convenient when I don't know what the exact numbers are. You could drag a selection (in viewer mode) and than type in whatever is displayed in the status bar, so in that particular use case:
An action "Crop to selection" after drawing a selection before using the crop tool.
Currently the crop tool totally ignores the selection, so if I wanted to do this, I would have to make the selection, open the crop tool, and then type the dimensions displayed in the status bar.
In the crop tool, visualise the cropped area on the image behind it.
Currently it shows nothing, so the crop tool is totally "blind". How am I supposed to know if I'm cropping what needs to be cropped?
In the crop tool, enter values to crop away, instead of width/height.
So enter how much to take away from each of the 4 sides, rather than being restricted to a width/height, sticking to the little 9-position grid. Granted, it's called canvas resize, not crop tool, so technically you could reason current behaviour is correct. But equally, why would left/right and top/bottom always have to be identical when not cropping from a corner? This is a severe limitation, iyam.
In conclusion - the current crop tool is a great start, but it really needs some more love. It's good enough for an occasional cropping, but it's too much faffing around when having to do a whole bunch of images where each border is slightly different.