Pretty Good
Last update was 8 years ago, last update for the iPhone was 2 weeks ago. That tells me that Celeris cares more about Virtual Pool 4 on the iPhone than the iPad.
You have three play modes. Quick Play, Pro Tour Career and Hustle Career. I like the Quit Play the best because you can turn on or off the aim line or tracking line or the ghost ball, I prefer not to have any of those on because it's more fun and more challenging, not so much with the other two. There's an option for the aim line so you can turn it on or off but the off feature doesn't work, so it stays on all the time I'm OK with that. The tracking line you can turn it on and off and that works fine but with the ghost ball there is two option to turn it off but that doesn't work so it's always on very annoying. As for the ball physics is not perfect particularly the Cue Ball it seems to travel further causing the Cue Ball to scratch more often than it should. As for the camera angles, you can set the camera angle for instance after the computer player shoots the a ball for a side view or end view at about a 25 to 30° angle that show the whole pool table but you can't do that for the human player so you have to zoom out with your fingers or use the top down view camera angle which I don't like.