From Bob Vanderbei:
As I’ve discussed with respect to other maps, I prefer the bidirectional color scheme (that is, I prefer the colors in Bob’s bottom map, which meet in the middle at white (actually, I’d use light gray) to the unidirectional scheme in his top map).
Either way, though, the maps show a lot. The second map, in particular, shows the general (but not complete) pattern of uniform partisan swing. These are simple but very effective displays.