Some possible steps for you to take–if, like me, you find that your GNOME terminal has suddenly taken a turn for the uglier–below the fold.
After applying a recent set of updates for Debian testing (wheezy), I noticed that the standard GNOME terminal emulator looked awful. Just awful–the widgets didn’t match with anything else on the desktop and the font was wrong, all wrong. Naturally, I assumed that I had messed up and so I un- and re-installed gnome-terminal (not recommended practice for a cosmetic issue like this), to no effect.
After a little research I learned that it’s because the new version of gnome-terminal (3.0.1-1) is a GTK3 app and expects a GTK3 window manager theme to be running, otherwise it uses widgets (scrollbars, buttons, etc.) from the fallback theme, which is what I saw.
Various remedies exist, but the most obvious one–“upgrading” to the most recent version of GNOME and the packages it depends on–isn’t available to GNU/Linux users of a more cautious bent who run Debian wheezy (let alone squeeze or lenny). You can install Adwaita, the default theme for GNOME 3 which is GTK3 all the way down, as it were; but it’s not the theme of choice for someone with a small display or an aversion to lots and lots of window chrome in general. gnome-look.org has some Adwaita-inspired themes that you might prefer. There’s at least one port of Adwaita to GTK2 out there as well; again, though, it inherits Adwaita’s predilection for shiny, thick padding around the edges of windows.
Until a more elegant solution presents itself, users of wheezy may have to stick with changing the font settings in gnome-terminal manually and ignore the differing appearance. At this point, the GNOME terminal looks fine in GNOME 3 on Debian sid (unstable), although the GTK widgets still look weird in window managers other than metacity / mutter.