The big solid blocks with weird textured backdrops are extremely distracting. It's hard to read the chat or see the raid frames against the bright green swirl, for example.
There are too many different fonts in your UI. Pick two at most (for example, you could use a more decorative font for combat text because it can be less readable when it's only used for short text strings like "4k" at large font sizes, while using another more readable font everywhere else) and make sure all your addons are using them.
The border on your unit frames does not match the border you're using for everything else.