It can do almost anything with the keyboard. I'd suggest just checking it out. A lot of people make changes to caps lock, shift key, left/right option/command, etc. I only do two things, setting fn to send hyper and swapping semicolon/colon. It's more about individual rules than a new keyboard layout (which is what Ukulele appeared to be in my 5 minutes with it).

Maybe other people can chime in on their uses, since I'm not the best to fully answer your question.