An interesting header-only logging library, spdlog, was recently posted on Reddit. A comment by Sean Middleditch sparked an interesting discussion on the thread:
"Header only" is an anti-feature. Fast compiles are important. PCHes only fix a fraction of the problems of header bloat. Avoiding 15 minutes of setup to get a library building/precompiled in exchange for months of lost productivity waiting for slow builds is a pretty bad trade off.
Here are some of the replies: