I like the extra bass that I get with no plugs, but when I plug the rear ports, there is a very noticable difference in the clarity and detail from the midrange. Voices become very crisp and articulate. This makes sense since the rear port would seem to be for the midrange driver while the front port is for the lower driver. Even with the rear port plugged there is still good solid bass extension.
With the rear port unplugged, there is bass you can feel. Pretty much sub-woofer level bass, but still not boomy. It's massive bass, but tight. I really like it with most music, but if I play something that is packed with deep bass its a little too much, but this is rare.