I, for one, love it when the menus are on top.

What I don't like, however, is that they are on the top bar sometimes, but not always.

Java Swing applications usually have their own bar. evince, Ubuntu's default PDF reader, has just some useless "About" menu on top, and everything important is under the gear icon in the window (which took me about 15 minutes to discover). And it's a default GNOME application!