Gameplay and the physics feel very good!
Art is a bit too minimal for my taste (especially the solid white bits could use some highlights/3d effect). I missed music a lot although I often turn it off in games. I'm a big fan of Pinball Dreams and Fantasies, so maybe I'm expecting too much when it comes to presentation.
I liked the little back table behind the glass although gameplay-wise it felt a bit bland back there. And at first I didn't recognize what it was until the ball was in there. Maybe add a reflection "effect" onto the window.
Also, most people don't use their monitor vertically, so I wouldn't make it standard, and please add moar blinkenlights!
Anyways the core of the game is very good which is the most important. Hope my feedback helps you a bit, thanks for making this. I also want to make a 2D pinball game one day :]