I like an application with an attitude.
Attitude aside, orpie is actually quite easy to use, and I have next to no experience with RPN.
Come to think of it, the last time I used anything RPN-ish was the last time I tinkered with orpie. 🙄
orpie wins points for me by using the full screen, keeping all the important tips on the screen and using the obvious keystrokes for the major mathematical functions.
On top of that, it handles trigonometric functions, octal, hex, binary, polar, and a long list of other fun stuff … most of which is triggered through the abbreviations menu.
The screenshot above is from Debian, because as luck would have it, the Arch version fails on some dependencies — ocaml-gsl, if I remember right.
Score one more small point for precompiled distros. 🙄