While in Marion for seminary classes, I went for a 3 hour solo paddle to explore the upper backwaters of Salamonie Lake and the lower section of the river. It was a beautiful night with calm clear skies. The water is not clear, but it seems pretty clean. It doesn't smell bad at all, and I saw very little man made pollution. I encountered one fisherman while launching, but didn't see or hear another person until I returned. I saw lots of herons, egrets, cormorants, and jumping bass. I made it back to the car about a half hour after dark.
The river is very, very slow as far as I went up it. It is wide, deep, and easily navigated. The upper lake region is full of stumps and trunks, making for an interesting place to paddle. If you're looking for a short paddle, I would recommend putting in on east side of the peninsula that I stopped at the top of. There is a short road that runs to the west side of the peninsula, allowing you to make a very short walk back to get the car, a very unique experience. This route would probably only take and hour and would be suitable for small children.