14 DAY TRIAL // There is a powerful trend in theme design that seems to take over everything, namely flat themes. Most of the themes are just interesting, but every once in a while one stands out. This is just the case with the Iris Dark Gtk theme.
You might not realize from a simple screenshot how good this theme is, but you will have to install it to believe it.
“Iris Dark is a flat theme that uses varying shades and tones to create distinction and a modern experience. It supports Gtk 3.10, Gtk 2 (using the Murrine engine) as well as Granite Widgets,” notes its developer on deviantart.com.
The theme should work on GNOME, but I tested it on Ubuntu 14.04 and it's awesome. The colors fit and, even if it's supposed to be flat, it doesn't feel like it. You will have to install it the old fashioned way, by copying it to the ~/usr/share/theme folder.
Iris Dark Gtk theme is still in the Beta stages, and I found some minor bugs, especially in Firefox, but I'm sure they will get ironed out.