Having tested this with a simple STL file, I can confirm that it produces surfaces and composites (relatively) easily, but I had some difficulty with solid generation. This may be an issue with the integrity of the STL mesh itself. Post-conversion editing tools do work but you will need some patience with your manipulation.
Available free for subscription customers.
Mesh Enabler for Inventor 2013+
"The Mesh Enabler application converts mesh features to solid base features or surface features. This function can be applied to individual or multi-selected mesh features or mesh feature folders.
After installing Mesh Enabler, right click on one or more imported mesh features of interest, and convert them into Base features (solids, surfaces, or composites) through a new context menu command. The graphical mesh data is converted into B-Rep Model data that can be used similar to imported solids and surfaces."