Oh what a true find in Vegas! I fix up pinball machines as a hobby so I'm always over the moon whenever I find a place with a plethora of machines. Unlike other pinball places I've visited however, you have to actually put money into the machines. The places I've visited you pay a flat fee ($7 for 40 minutes of free play for example) so you can try literally every machine.
I only played the Woah Nellie which is the newest pinball machine out there. Wasn't impressed with the game but that's not a reflection of the place. The only gripe I had was about the AC/DC machine not being in great shape. The lower playing field (which is below the main field, it's a mini pinball game that looks like hell) needed to be cleaned bad. I know these machines get beat to hell since they get played all the time, but there's nothing wrong with cleaning them every now and again.
This place is totally worth a visit though. Love it!