I didn't find anything wrong with level 8, in fact i got it on my 3rd try.
Level 9 was the killer for me, i feel the placement of the two disks are off.
The angles look like they are perfectly set-up and the game gives you a 2 bounce par which even further suggests the obvious angle strategy but no matter how many different spots i place the bomb i can't get the par.
Other than that it's a neat game, not sure what people are complaining about when it comes to the physics being off.