I totally agree with this. I got an iPad Air and was really expecting a fast, fluid experience from the latest A7 chip and new hardware. Whoa, was I disappointed to find gestures are laggy, switching between apps is slow, jumping around the system is sluggish and painful. It came with 7.0.3 pre-installed.
I used an iPad 4 and my iPhone 5 on iOS 6 and I cannot believe how fluid and wonderful they were together. Using it was genuinely fun. iOS 6 was ready and waiting for you, iOS 7 is reluctantly carrying out your commands in it's own time.
Interaction speed with an OS is possibly the single most important thing you can right and so far with 7.0.X I'm pretty disappointed. I find it harder to believe that iOS 7 UI is slower considering it's so much simpler - way more single colour space, less shadows, no more textures and gradients to chew through. The opaque stuff is clearly eating into ti but even when turned off (Increase Contrast setting) it's still much worse than iOS 6.