It's nice photography from an artistic point of view, but i always dislike Greenpeace's exaggerations. Which is not to say Chernobyl wasn't a disaster. The exact extent of the damage is incredibly hard do measure, but also likely below what it was expected to be back in 1986.
What we should really commemorate here, imho, is the horrible response of the suppressive Soviet regime, the relative apathy of those currently in power, and lack of support from the richer nations.
Haven: An increase in cancer rates in wildlife is insignificant as most animals will die in the wild before cancers really develop, and those who get sick and die will simply be replaced with healthy animals, a slightly higher death rate doesn't have to jeopardise the species' survival. In fact, an increased rate of mutations may help a species evolve faster, too.
The forest around the reactor was called the Red Forest, because the leaves turned red from the radiation, turning the entire forest red after the disaster, then they fell off. The fact that the trees survived, being unable to move and slow to reproduce, is amazing.
And if anything would wipe out the human race without totally destroying the earth, you can safely assume some wildlife will survive and flourish in the period after.