Not too terrible. I've reupholstered several seats ranging from 12" round barstool to ATV's and antique bicycle saddles using genuine kid skin or marine grade PLU vinyl.
The trick to nice corners is 3 parts.
1. Do the corners first and in opposing pairs.
2. DO NOT be afraid to stretch your material, it's going to stretch and loosen as it wears so the tighter you can get it to start the better
3. Minimize bunching with a razor; make slits and/or cut out triangular notches and overlap underneath where you're shooting staples and won't see.
With practice using that combination you'll be able to make just about any seat look like a factory wrap.
Just random examples...
With bicycle saddles, I always do the nose first because where it's the narrowest point it causes the most bunching up, but also has the best grip to keep the movement and slip at bay when pulling the material tight to the rear center for a quick tack before doing the rear corners.
A symmetrically round bar stool would be done like Tightening down a cylinder head, but a lot more points (start, cross and pull, staple, cross back and pull, staple, repeat).
After leaving a 2" gap between each stapled point until you've come back to the start, you'd then begin the process of tuck, tighten, staple again following the original cross and back pattern.
