I'm glad I'm not the only one bugged by this. My previous car would never let the speed get more than 1mph off of whatever I had set it, even on a hill, but Honda's is loose at best. 2-3mph below isn't at all unusual if the slope changes, and it will overshoot occasionally as well.
I'm also with KentuckyKen on the extremely light touch acceleration. I don't expect the cruise control to floor it to get back to speed, but it is such a gentle touch that it feels like you're going to be bothering cars behind you. This is true for both ACC while following someone and for increasing the speed or hitting resume after slowing down. Conversely, if you reduce the setpoint, it decelerates surprisingly aggressively instead of letting the car drift down more gradually. Basically, it's the exact opposite in terms of aggressive speed management than what I'm used to, and what I want.
Also annoying: The cruise control in every vehicle I've ever driven (Acuras and Hondas included) will essentially hold the accelerator at a certain point, but if you push it past that will let you accelerate the car. The Clarity, however (and this might be an ACC feature, never tried traditional), will disable cruise control if you touch the accelerator.
This is really annoying when trying to set it, because I'm used to holding the speed I want, turning cruise on, waiting a moment to let it set, then taking my foot off the accelerator so the cruise control takes over smoothly. Now when I do exactly that, the cruise control waits for 1-2 seconds after I take my foot off the accelerator to kick in, during which time the car will lose 2-3mph of speed (maybe more if I'm going uphill), before it brings it back to where I wanted it. As far as I can tell, it's impossible to turn on cruise control when you're at a particular speed and actually smoothly maintain that speed.
Anybody know a trick to workaround that?