Simple question: What are the pros and cons, as well as overall opinions, of outsourcing work as an independent game developer? (For example: paying an artist to draw characters, or a composer to write music, etc.)

In particular I'm interested in the case where the developer (be it an individual or a team) can still complete their game to an acceptable standard without hiring somebody. (For example: maybe they're "ok" artists, or can use music from a free library.)

(Ideally I'm looking for answers from people with experience in this area.)