Regardless of what other have said, I think this game is hilarious. It's got some trial and error, it is true, but I've had loads of fun with trial and error games in the past - and this is no exception.
The game itself is fairly simple: place traffic hazards to change the flow of traffic. The drivers have positively *insane* AI, and pull some ridiculous stunts with it. Changing lanes into oncoming traffic, not bothering to slow down to avoid the horrific pileup right in front of them...
The scariest thing is how *real* it feels. I think this is in part because, although the drivers seem to have no sense of self preservation, they actually can drive autonomously around the world.
This combination of factors makes for some absolutely hilarious outcomes. It was frequently trial and error, but most outcomes ended in some ludicrous and tragic smash that seemed so outlandish that I was wracked with laughter. I had a great time playing around with this. While it got a touch tedious towards the end (where the levels were more grid-like, instead of freeform and unique), both I and several of my friends had a very... amusing hour.
If you don't mind some guesswork, and enjoy the uncannily realistic stupidity of the drivers, then I thoroughly recommend giving this a try.
If a sequel ever came about, I'd recommend that levels stayed closer to the earlier levels' more sinuous design, though!