>Features that are buggy or inexplicably complex is not fine.
really depends on so many factors that this isn't a good general sentiment. Sure, if this is a professional grade tool targeting corporate, it better be polished or have excellent support for when stuff breaks. If it's some small scrappy tool handling a complex task with all kinds of edge cases I can give some leeway to the UX and even some very esoteric use cases.
vector graphics comes immediately to mind. I won't be too griped if Krita as a FOSS has some subtle bugs. I can at the very lest throw out an issue to at least bring awareness. I'd be much more miffed if Illustrator had some issue given how closed up and hard to contact Adobe is if you're not a million dollar business (not to mention Adobe's general philosophy of how they approach software these days).
Attitude is a factor, but I do take into account the problem space when evaluating feature completeness.