Baloo,
I've never played a UDOT. I was considering one, but knew that i wouldnt satisfied unless i had an Environmental.
The entire driver was playing it as a kid - if it weren't for that, i wouldnt have one now. When i was 8, i stepped out of the cab in awe and dazed. This was the 80s, it was impressive back then. I remember thinking that i just played the future of gaming! And i liked the game - there werent many games where you controlled a person shooting things at another in 3D at the time. Lots of space games / cute games up until then, it may have been one of the first third / first person "shooters".
In contrast, my kids now (oldest is 7) played and i could tell it wasnt the same for her as it was for me... Kids today are spoiled i tell you.
Still, the experience is something else - alot of thought went into the design.
First off, you have the layers of artwork on the playfield - Tron landscape and some bezels behind a two sided mirror. The mirror is for the reflection of the monitor back to the player so as not to hide the artwork behind it. You can hardly tell you are playing off a mirror. In fact - my wife was in the middle of a game last night (last time she will ever play it

) and i mentioned she was playing off a mirrored image, she was pretty amazed by that.
Next, the game has a relay board that activates the light fixture beyond all the Tron Scenery. So, none of that depth is seen (its just the text from the attract mode), until you start it up, which dramatically and in sync with the music fires up the light, all of the layers appear at once, kind of like you are dropped into the Tron world.
Another relay serves as a strobe for the lights below the players feet and on the CP. They flash wildly when you get hit. Its actually scary and will "shock" first time players, probably thinking they broke the game (its the equal to a Pinball knocker).
Add in the speech, and yes, its all smoke and mirrors done pretty well. The gameplay itself is pretty good too - like 3D Pong.