One of my design goals for AFL was to make it very simple to use - because there's plenty of fuzzers that work OK when you dial in 50 knobs just right, but fail spectacularly otherwise - basically ensuring that nobody but the author can really use the tool to its full capacity.

While AFL++ is cool, it sort of ditches that philosophy, giving you a lot of options to tweak, but not necessarily a whole lot of hope that you're going to tweak them the right way. So, that's one gotcha to keep in mind.