It doesn't matter that they met, although the photo is clearly embarressing, as was Rumsfelds. The Japanese PM met with North Korea's wackjob dictator just recently, it doesn't mean they are best friends. Diplomacy would get very cumbersome if you completely ignored all the bad people in the world, sometimes you have to talk with them.
What really matters is the context of the meeting. Junichiro Koizumi went to North Korea to secure the release of the children of kidnapped Japanese citizens, nothing wrong with that. John Kerry was trying to avoid bloodshed in Nicaragua. You may or may not agree with that, but it certainly isn't as controversial as some would clearly like to make out. Donald Rumsfeld went to Iraq to sell weapons to Saddam. Personally I see that as being significantly more controversial than the other two examples, but then whatever, make up your own mind.
Basically if you're conservative the photo is cast iron proof that Kerry is a clone of Stalin, if you're liberal it's vile right-wing propaganda, and if you're sane then it doesn't really mean anything worth considering.