For most of my projects, Paint.NET works great. The Perspective (transform) tool is the only feature that keeps me from using The GIMP for only the most advanced features and filters.
While it should be familiar for anyone who knows Photoshop or the GIMP, What I am talking about is a tool that will stretch or distort a selection by moving the corner points closer together or farther apart.
I have found this to be a very useful tool that would be a welcome addition in Paint.NET.
-Jc