In the majority of cases for me it was most noticeable on a flat road, or with a minimal incline. More often than not coming up to traffic light controlled local roundabouts that I know roughly how long it will be until the lights change.
Coming to a stop, clutch down, brakes on. Keep clutch down and 1st engaged because the lights will be changing very soon. Go to pull away, light throttle and car moves on bite point, hill assist still biting so more throttle applied whilst bringing clutch up further. Before you know it the car either kangaroos or you launch off into the distance unintentionally.
Now I will concede, I have not experienced hill assist in any "premium" brand cars or even automatics for that matter, but I have noticed it in most cars I have driven with it.
*edit* - I lie, I didn't like it in the automatic Jeep I had for a few days once too
I just don't like how it feels