Is a corner roller or corner pad a good tool to use to cut into corners when painting?
I've tried a bunch of tools for cutting in corners/edges (the worst part of the job, IMO), and always end up going back to using a paintbrush.  There's not enough of a texture difference to notice it unless you have your face ON the wall (once it's dry), and it's much easier to deal with.

My family helps each other with painting, and my sister has textured walls. In that case we did use foam rollers to cut in, just for the better coverage in the texture. As long as you have plain, flat, drywall, brushes are the way to go IMO.