The rollers are clean and it plays fine I think. I don't have anything to compare it too, but I had a fun game of Golden Tee just now and I've never played that before. I also played Missile Command, but I've only played it on console games. Marble Madness was fun also, I can't tell where the sensitivity is supposed to be, does the marble only move while you spin the TB normally, this TB doesn't have much spin after you stop rolling it, it will continue for a bit, but not as long as my old Trackman MarbleFX.
I don't have any calipers here, but using my tape measure, I'd say it's 1 3/4" ball. It seems like a good size for my panel since I have some size concerns. A little chinsey maybe but if I upgrade it'll only get bigger so I can make a hole for this one and then go bigger if I decide I love TB games and hate this TB. I may also look at using my Trackman, but it is shaped weird and I don't think I want to cut it up, I haven't used it in forever, but I loved it when I did use it, it's also probably more like 1 1/2 inches, but that's only from memory.