Recs.
Updated
Yakuake is a drop-down terminal emulator in the Guake style, but based on the KDE Konsole framework. Its features include: smooth roll-down and roll-up animations, a tabbed layout (a la modern web browsers), configurable dimensions and multi-screen positioning, skinnable themes and a sophisticated D-Bus interface.
Specs
Pros
Pro Very customizable
Almost everything is customizable: from split view, fullscreen mode, configurable dimensions to animation speed and keybindings.
Cons
Con KDE Library dependencies
While not an issue if using KDE, when trying to use this terminal in other desktop environments or window managers, there will be a large amount of dependencies tied to the app. This makes for a large install size. For those trying to keep their desktop lean, this may be an issue.
Con [OLD] Depends on KDE4 runtime
UPDATE: It will probably be ported soon (I think they might do it by Plasma 5.6).
Yakuake still has not been ported to KFrameworks and as such pulls KDE4 runtime dependencies with it. This might become a problem when KDE4 is dropped from Linux distributions (e. g. Arch Linux).