I only like to cover the most tasteful themes for iOS and Mojo is a brand new addition to the Cydia theme collection.
Designed by Kubilay Sapayer, from the Netherlands, he has put together a stunning new theme for jailbreakers to make use of.
The theme isn't exactly flat but it isn't entirely skeuomorphic either. It uses flat colours and minor shadows but has a very nice glossy effect too. They actually look like sweets, they're almost edible!
In terms of actual glyphs on the icons, they're very minimal and to the point. No fancy stuff here, just easy to read icons with very bold colours.
Kubilay has been nice enough to give the theme away for free, so you should be able to find it on Cydia right now.
It might not compete in terms of how many icons there are compared to other themes, but what can you expect from something that's free.