Part 3 of Neil Brown's "Ghosts of Unix past" series has an interesting take on signals. The conclusion is that "signal handlers are perfectly workable for some of the early use cases (e.g. SIGSEGV) it seems that they were pushed beyond their competence very early, thus producing a broken design for which there have been repeated attempts at repair. While it may now be possible to write code that handles signal delivery reliably, it is still very easy to get it wrong. The replacement that we find in signalfd() promises to make event handling significantly easier and so more reliable."

https://lwn.net/Articles/414618/