There are lots of Cydia themes available for iOS but I only like to cover the best - Kiwi is one of them. Kiwi is a brand new Cydia theme which launched just this week.
Kiwi has over 100 custom icons and it covers all the default iOS apps. It has a customised version of the notification centre, lockscreen, music player, messages and phone dialer. If you have Auxo, the icons for that will also be changed.
I've published posts on Jaku and Circles before, those themes have a very unique style, drifting away from iOS' glossy style. If you like the default iOS gloss, Kiwi will be perfect for you. All the icons follow the same glossy style but they're a lot more detailed and quirky. Though the messages app in this theme has a flat design - but I personally think it's awesome.
It's available on Cydia now for $2.99.