I checked these out at Evo this weekend.
I had preordered the Asteroids and Centipede ones, mainly because I am interested in the trackball/spinner controllers. I did try the Rampage and Street Fighter II cabinets also, though.
The monitors look like cheap TN panels, with mediocre viewing angles. That said, they're not horrible screens and are pretty servicable if you're standing right in front of the cabinet.
The joysticks were pretty terrible, I had a lot of problems doing shoryuken-type motions, and at least one stick was already flaky and broken (of course, maybe they weren't built to true arcade durability standards and they are out on public display at Evo). They are their own custom sticks from what I can tell and they don't look like they mount the way that real arcade sticks mount (didn't see four screw holes near the opening for the stick in the control panel, so not sure how they are mounted into the cabinet).
The worst thing is that the trackball and spinner are nearly unusable. Real trackballs and spinners are analog controllers, for each axis they output two square waves as a signal with the phase of the waves indicating direction and the frequency of the waves as velocity. These controllers felt very digital, sort of like they had discrete steps like a rotary encoder. This makes makes many of the games unplayable IMHO. On the spinner you can actually feel the individual stops. For example, if you want to move quickly in a game like Major Havoc, you'd spin the spinner quickly, but because it seems like they are using an encoder if you move the spinner fast enough you can seem to wrap the spinner around and actually cause your character to move the WRONG way. If you spin the trackball quickly you get jittery, stuttery motion in every game I tried (Millipede, Crystal Castles, Missile Command).
I'm kinda crushed that these are IMHO not very good and I just cancelled my preorder :( I think that if you're into the joystick controlled games then you'll have a better time, but I already have a real cabinet so there's not much point for me personally.
One more point of trivia - Gauntlet in the Rampage cabinet is the 2P version of the game, because the original Gauntlet had one joystick for each of the four characters. With only three joysticks one character would become unplayable, so they are using the 2P version of the game that allows character selection at the beginning of the game, leaving the third joystick unused.