While I’m a big fan of Jim Butcher’s Dresden Files, I didn’t thought his short stories would be any good. To me he looks like the type of writer who isn’t suited for the short form. Someone who needs space to really get the plot going and establish place and characters. While that may be true in general (he hasn’t written short fiction outside of his usual playgrounds), I liked his Dresden short fiction more than enough.
The stories collected in Side Jobs don’t feel like abandoned novel ideas or cut material. Each of the stories has just the right length and manages to stand well alone. That said, I do expect they do work best when you’ve read something of the bigger canon. Whether they are interesting enough on their own is something I can’t say. I think yes, but I don’t really know.