(This is more of an opinion on the new look & feel, than a bug.)
We have just installed and pushed Mingle 3.3 to our user base.
So far, almost all users have complained to me regarding the properties area on the cards. They site the over abundance of white space and the reduction of the font size of the properties for no gain. White space has increased both horizontally and vertically causing more problem than good. Some users are complaining that the new font is harder to see. Using Zoom to offset this issue is not a solution. Most users are saying that they like the old configuration better. We are using FireFox 3.6.8.
I've attached an example of what we see.