Rode it a couple of times tonight... it's a trip. We joked that whoever designed it was on acid, and I mean that in the best way possible. It definitely had a Tron-like feel with an emphasis on dark shapes and neon lighting. The whole experience is pretty abstract visually; not a lot in the way of physical set pieces per se (although there is one very cool SSE '94 style model city you drive by), but lots in the way of visual effects like laser scans of your car, lightning strikes, projections of lines, etc. It seems very narration-focused; I didn't understand much of what was going on my first time on it because I was more focused on the scenery and the movement of the car, but when I rode it my second time I realized the narrators were describing everything that was happening.
It looks like the effects are the same for every car in terms of physical ride experience, but how your personalized virtual car would have performed in each test is ranked alongside other riders on a screen after each scene. Pretty cool concept but it wasn't working when we rode; they were just displaying default example cars. I'm sure it's one of the things they'll get working for the finalized version.
In general, I loved it. It was interesting to see how WDI could bring its recent focus on interactivity to the table and impact ride experience in a truly meaningful way, without overpowering the ride (SSE), feeling fake (M:S), or turning the ride into an all-out video game (TSMM). This is something I never, ever thought I'd say about Test Track, but it is clear that it is now one of Epcot's forerunners in actually delivering on Future World's theme and visual style, alongside Spaceship Earth and the Land building. More bizarrely still, upon reflection, it occurred to me that this is my favorite of any of the three attractions that occupied the Transportation pavilion, and I've been on all of them (and dearly loved World of Motion). So that right there is an accomplishment. Kudos to everyone involved.