I have been evaluating redmine for about 2 weeks and I would like to suggest some UI improvements:
The indicator for new, modified, deleted line in a file could be bolder (make it looks more like netbeans: green, blue and red), on rubymine I could hardly tell the difference between new and modified lines. It's even hard to see changes indication.
The active tab could also be more visible too. (maybe with highlited background). and clearer indication of modified or new file (more contrast on the blue or green filename).
Use more padding everywhere. For example on the settings filter, there is no padding at all (http://skitch.com/e-reynardmh/giqnp/tmp ).
Many of the UI looks like it's too cramped, which makes it look like an unfinished product.
Sometimes the little detail is what makes something much better.