Everything frantic and moving to rapidly is a pain, but that isn't my biggest reason on hating dynamic themes. The fact that the firmware updates add new icons, which are never updated in themes bugs me the most, it makes it feel outdated, and from there I'll never use it... what makes this worse is that applies to all the overpriced themes too. Personally, I love the Fury theme's icons, but as said before me, the wallpaper is too frantic, and it is already missing icons.
What I'd like is the ability to mix and match themes- I'd like to see the MotorStorm: Arctic Edge dynamic theme background and Fury dynamic theme icons merged on my screen. I really hate how the Arctic Edge proves my point on icons (<2.70 chat icons WHY?!) and has the best background, while the Fury theme has the great icons and terrible background.
In summary: UPDATE THE THEMES, and bring in the ability to MIX 'N' MATCH THEM!