I thought they were brilliant in their simplicity. The secret to great communication with graphics is in boiling them down to a point where you can look at it and see immediately the point being communicated.
On a side note, I have this graphic on my wall at work, because it is widely considered to be one of the best graphics ever created to convey data at a glance...it describes Napoleon's army as it invaded Russia, and you see the scale, time, distance, temperature, and casualties all in one glance, and it conveys the utter defeat, horror and hardship of that army. One can almost see the bloodstained snow, frozen bodies and starving men just looking at it: