Window snapping on portrait-oriented monitors currently doesn't provide a good user experience: the snapping areas left and right are not really useful in practice. I suggest that we rotate the snapping areas for portrait mode: have the top and bottom snapping regions each tile to the top and bottom half, whereas left and right maximize the window. IMHO, this makes the snapping feature significantly more useful in practice.
Before Patch
After Patch
Behavior for unrotated monitors remains unchanged. If you're not comfortable with changing the default here, we could also make this inversion opt-in via a setting. Personally I believe the new behavior to be the saner default, though.