Depends on the iPad, obviously. iPad 4 is buttery smooth, for example.
I'm running it on an iPad (3rd iteration... the first retina iPad) and I can't tell any difference in "snappiness" from iOS6 ... just as responsive.
Third generation is OK, actually I really like iOS7. My wife is very mad at Apple. She has iPad2 and after upgrade hers is slow as hell. She wants iOS6 back.