Ever since Doom II's Dead Simple, mappers have been crazy over the 'simple shape' map. And why not? After all, DM-Morbius was a great cylindrical map, and they're easier to make than the whole interconnecting room mess. However, the vast majority of these maps go on to be lousy, and in this sense DM-Thunderdome certainly won't be lonely.
The map is essentially laid out like two cones enclosing a space. There are two ring-shaped platforms along the edges, a catwalk composed entirely of transparent textures along the top, and an unidentifiable cylindrical type thing in the center. The catwalk is enclosed except for a couple holes, but uses transparent textures, making you feel like you're in a gerbil tunnel. The central cylinder has a hole in it, and a couple tunnels leading to sniper spots which are very hard to see players in. Gravity boots are needed to get out of this tunnel, and if you somehow use them up, well you just have to wait around for them to respawn. Item placement is the usual "one of everything" job, with no real thought to placement. Bots aren't very intelligent at all, and avoid the central cylinder completely; grab your sniper rifle and go into one of the nests and you can just plug away until you fall asleep.
The texturing, as I mentioned is just something else, and I don't mean this in a good sense. There's very little worse than using the "Digital Extremes" logo in your map. Scrolling. On a transparent texture. If that doesn't put you off, there's the Epic and Unreal logos here too, all scrolling of course. Transparent textures are, as you might imagine, used very liberally, creating HOM effects in some places, and dropping framerates nearly to a slideshow in general. Lighting is there simply to get the job done, being of uniform brightness everywhere except for some darkness in the central cylinder.
If you're looking for a single-room map to play folks, there's plenty better, some are included on your Unreal Tourney CD in fact. I wouldn't waste my time on this one if I were you.