We are currently evaluating RubyMine to use as our main IDE and we really like it. But (there is always a but ;-)) there are two things we were not so happy with.
First we have some trouble using the right click context menu. If one clicks the right mouse button (e.g. in the project explorer) the context menu comes up, but then imideatly closes again if the mouse button is released without doing a mouse movement (at least under Ubuntu 10.04). It doesn't feel natural and is not the same UX as normally under Linux or Windows. Any chance to improve this, or does it just depend too much on the underlying Java? We tried it out with several L&F, but it doesn't feel right in anyone. Also after switching themes it happens that those context menus pop up on completely different locations than the mouse cursor is (a restart of RubyMine fixed that mostly).
The second thing we were missing is the feature to reorder our editor tabs. I use this one quite often (it's nearly standard in most editors) and I am not sure if I can really live without it. Are there any plan to integrate that feature in the short time?