Are you going to get involved in the local politics? If no than you are no more likely to be kidnapped in Agusan than in Luzon.
There were some flash floods a few days ago and the area was severely damaged by Typhoon Bopha in December 2012. I don't know the current situation but do a little more checking if you plan to visit in the near future.
When are you planning to visit Agusan del Sur? I hope it's not during the first quarter of the year, as this is their so-called rainy season. But I've been to that province many times, and I found out that a day there isn't complete without a rainfall or drizzle.
It's located in the northeastern part of Mindanao, which is safe to travel around. If you're interested in flora and fauna, then Agusan del Sur is the place, as there are lots of woods that are only found in that region. The Agusan Marsh is their main attraction, where you'll see migratory birds and floating communities. The town of Bunawan is home to Lolong, the largest crocodile in captivity. There are waterfalls too; I recommend Tugonan Falls in Prosperidad.