I too had to complain about this. It grinds horribly even if you are well skilled in using a clutch. The worst is on a level service like a red light and it decides to engage when u attempt to go into first.The hill start assist keeps your car from rolling backwards when starting out in 1st uphill. When you start to gas and release the clutch it will auto engage the break. It feels like you left your parking brake on at first. As you start to move it feels like ABS braking but in reverse for a second or two as you increase speed. It is useful in bumper to bumper traffic uphill and can help to save a little gas, but it can be very annoying when you are barely going uphill and it kicks in needlessly. Sometimes I will feel it engage going from first to second uphill and I really wish it wouldn't. I wish I could turn it off.
My Subaru's hill assist was much less obtrusive, but that car also had much more torque so it really wasn't needed if you are good with a clutch and hills.