Please stop it with the "coding ligatures" already. They are not helpful and only serve to obscure the code being written. This has got to be one of my least favourite trends in programming aesthetics these days. For a font claiming to "follow function" to devote so much effort to sacrificing function for the _vogue du jour_ is especially rich.
I mean... The existence of ligatures is almost by definition strictly aesthetic. And on that measure, it either brings you a smile to notice that f and i, for example, are joined; or you didn't even notice it. That is, I won't claim they help readability. But they do make me smile, and don't seem to hurt. (I'm assuming they disappear on copy operations. Mac OS' habit of replacing -- with a longer dash is painful when…
When I'm reading fiction, I generally don't mind ligatures. I find them oppressively obscurantist in any situation where I want to know clearly and distinctly what each character is -- i.e. code and science/math/engineering.