Classic: figsize (8, 6)
v2.x: figsize (6.4, 4.8)
fontsize: 12 pts in both cases

Together with the infamous outward ticks, this change in figsize wreaks havoc on label placement and axes positions. For a single default subplot, possibly adequate adjustments have been made, but the situation for multiple subplots looks hopeless. Here is the default 4-panel figure, without even trying to add any labels or titles:

Possible solutions:

1. Restore the old figure size.
2. Reduce the base font size
   In either case, of course, all positioning parameters will need to be reviewed and adjusted.
   I omitted one option: I think that increasing the subplotparams wspace and hspace enough to make 4 subplots look reasonable would leave too little room for the plots themselves.

I think the change to figsize is also responsible for many broken gallery examples as well.

The rationale for reducing the figsize was that (8, 6) is too large for most publication uses, and that with the increase in figure.dpi to 100 to match savefig.dpi, it is also too large for the screen, making it hard to work with multiple figures, and, depending on the user's screen, possibly even triggering resizing, which destroys any attempt to design a layout with fixed dimensions.

Therefore I think that the best option might be the more painful one: drop fontsize from 12 to 10, and adjust everything else accordingly.