I agree with you since when ios6 launch.

Now I update ios7 for some reason. 

i updated my iPad 3 ady.. nothing problem.. everything is ok.. only transition animation looks lag while closing apps only.. but i think it's the motion.. i will upgrade my iphone 5 later while to compare see.. whether it's my iPad 3 problem or original UI transition animation problem..

iPhone 5 transition animation different with ipad.. iphone 5 very smooth.. even i full restore my ipad as new ipad and new settings, the transition animations is still same there.. (only occur when closing apps) the animation seems lag.. i need to ask my friends other ipad 3 and 4 test see.. but i think different hardware there..

other than that, iOS 7 in ipad and iphone are looks good..

there are something i dont like in iOS is about the when phone/ipad is locked, people can turn off my devices by just press and hold the power button and turn off.. no security at all..should make it have to authorize to turn off the phone..
**EDITED: Transition animation only lags when i use 5 fingers to close up the apps.. No lag noticed when I use home button or assistive touch home button..

for me i didnt feel lag in keyboard typing.. both works well in virtual keyboard and bluetooth keyboard..

iOS 7 didnt add special features for us.. but i quite like the overhaul SAFARI (friendlly and easier use), Bigger notification center.

dislike and the problem still exists to me: anyone can turn off the phone/ipad even in locked status by pressing power button.. i hope apple can fix it by at least need autherithecation only can turn off the phone..
2. when using gesture 5 fingers to close the apps, ttransition animation seems lag 1/4 sec. hope can fix..
overall, performance didnt reduced even in GTA, asphalt 8, Infinity blade.. still smooth but not the max framerate. but still acceptable.

tmr i will help friend update ipad 4 to ios 7 due to i got faster data speed and he dont have data speed.. after that i will compare within ipad 3 and ipad 4 to check whether any big difference..

Updated my 1.5 year old iPad 3 bought from SG.

Keyboard unresponsive and lags.
Photos app crashes for no reason.
Rotation lags
Control Centre lags

Overall, almost everywhere lags. No idea why. On my 4S, quite smooth. Both updated via OTA.

yea.. even i updated my friends 2 ipad 4 also same problem.. dont worry.. its not about our ipad3 is outdated or hardware limitation, but its apple didnt optimize for ipad..

Stumbled upon this thread, I didn't know that so many of you guys are facing this issue. Honestly, I hardly feel any lag with iOS7 on my iPad 3 especially now with the latest patch where I prefer the fade out animation instead of the moving animation. Quite smooth on the iPad 3. Sadly I can't say the same for my iPad Mini