Ease of use after first configuration. Ability to save passwords. Ability to setup single-click links to dozens of boxes all in one screen. Ability to open multiple sessions at the same time. Intuitive and easy to use drag and drop interface.
Can be a little friendlier to file copies from one session to another. i find that I have to drop file locally and then grab them again to get to teh second session. It would be nice to drag from one session to another without the middle step.