I admit, I'm not a big fan of custom themes and all that jazz. In my opinion most of the themes that come out look a little on the generic side, but I can understand why some users would be fond of the custom element that it adds to the iPhone.
WinterBoard is the de-facto standard when it comes to adding custom themes to your iPhone, and it's a prerequisite for quite a few of the tweaks that are available on Cydia as well.
One of my main gripes with WinterBoard is the fact that it can interfere with the text on your Home screen. The text for the app names turns into a grey, shadowless, illegible mess as seen in the screenshot above.
To try to remedy this issue, WinterBoard comes with a "White Text Labels" option in its 'Select Themes' section. This helps alleviate the issues surrounding the color of the text, but unfortunately still lacks the shadows that the stock look is known for...