I can remember first seeing a GTK+ version of qalculate! around 2009 or so. As a replacement for a generic desktop calculator, it does a fine job.
It never really caught on with me, mostly because I don’t have need of a desktop calculator very often. galculator is okay for my needs, in its GTK2 version, thank you.
There is a command-line version of qalculate! that Debian calls “qalc,” which I have seen called “the greatest calculator ever.” I won’t say whether I agree with that or not.
qalc follows an interactive style, in the same way as bc or some other calculators, but can also calculate CLI-wise. It has onboard help, which is always good. It can access the Internet to get up-to-date conversion data.
I also like that by default, qalc shows you your entire calculation spaced out and arranged, rather than just spitting out an answer. Of course, there is a “terse” flag if you prefer the opposite.
There’s not much to dislike in qalc, but as I am finicky today, I have to be honest.
It seems that qalc (and by extension qalculator!) is trying rather hard to become all things mathematical. While there is convenience in that, I have this nagging prejudice in the back of my mind against programs that try to do everything at once.
I don’t care for audio players that double as music managers, I don’t like file managers that try to be hex editors, and I don’t want a text editor that tries to be an operating system.
All that said, I will temper my dislike by saying that qalc, to the best of my knowledge, stays within the mathematical and doesn’t try to work as a chat client too. I respect that. 😉