It's unfortunate that Gottlieb machines from the 90's get such a bad rap amungst collectors. The build quality under the playfield is pretty awesome, and the reliablility of the board set has proven itself over the last 20 odd years. I have owned a couple in the past, and they gave me little trouble at all.
One which I had owned and kind of regret parting with is Super Mario Bros. I think the main reason I still wish I had it, was because it was in such great condition. I got hold of it back in 1995, so it only spent 3 years out on location. These days it's very difficult to find one without a trashed cabinet and worn playfield.
The game itself is a Nintendo/Mario fans dream. They really nailed the theme perfectly with appropriate art, fantastic sound (although it did get a little repetative) Plus really great dot matrix display animations that included the video mode where you'd use the flipper buttons to play a mini Mario game running across the screen jumping the gaps.
The light show was pretty cool as well. There's 4 prominent clear dome flashers on the playfield, and when I owned the machine I put cellophane over the lamps to add a little colour. Of course now you can simply purchase the coloured flash lamps :)
It's not a difficult game by any means. There's a kickback on the left drain, a drop target that acts as an up post between the flippers. Plus if you happen to start "Invincible" mode, it's almost imposibble to lose the ball for around 30 secands or so. But in saying that, it still provides a decent challenge. It's very cool when you finally get the "777" on the slot machine for 200 Million, and the "catch up" feature in multi player games where you could be coming dead last on your final ball and all of a sudden be awarded catch up where your score gets boosted up to whatever the current leaders score is, makes for some interesting times :)
So it's a thumbs up from me. If you ever get the chance to play or purchase one, don't overlook it.