Ball-physics seem pretty good. You can pan up and down a bit (X and Y), set the "english" on the ball by holding the B button and adjusting with the d-pad, fine tune your aim with the shoulder buttons and you shoot with the A button. No touchscreen use required. Plays standard 8 and 9-ball as well as a UK version that uses different color balls. There's single player, 2-player and league modes. I only tried single player mode.....within that is quickplay, league, tournament and a extra game called "killer" where you have 8 lives and must make a shot or lose a life.
First problem I've seen is that it's hard to line up a shot. It doesn't give you a wide enough view of the table and the DS isn't exactly the highest resolution for making fine adjustments on. No tracers to give you any idea which way your shot is going to go, an overhead view is on the bottom screen while a 3D view is on the top screen, but neither view is truly good enough to properly judge a shot. Still, the first game I played (8-ball) I only lost by 1 ball, so maybe it's not so bad once you get used to the game a bit.
Certainly the best pool game I've played on the DS thus far, even with its flaws.
It trims to 4.68 megs using NDSTokyoTrim, so it's not like you'd be wasting a lot of space to check it out.