This editor has some nice features but also some obvious bugs. On another level, it is crossplatform (usual warnings apply) using the wxWindows widget set. Developers who write crossplatform programs are usually from the Linux community and thus have much lower standards for interface polish than Mac users. And the widget sets (GTK, wxWindows, Qt, etc.) that they employ hinder them further in making an interface that resembles what Mac users are accustomed to. And it seems that they tend to do little testing on Macs. I don't know about this project in particular, but I've interacted with developer teams that don't even have access to a Mac.
Another gripe that I have with the plethora of editors including this one is that many of them cater especially to Python and maybe a couple other languages-du-jour and treat other languages as second-class citizens. Editra recognizes Ada for syntax highlighting but many other features are broken for Ada, including code folding, indentation guides, and no linking from compiler errors back to the relevant code line. (The Ada to which I refer is GCC Ada, aka GNAT, an official part of GCC.)
Interface problems are too numerous to mention, but here's one: When a file is changed from its version on disk, the red close button should have a dot in it; Editra does not do this. I'm sure I could easily list at least a dozen problems like this.