I would love to see a technical test of traffic information (how quickly the info is updated, etc).
But there is now so much information on traffic on both google and apple maps (reds, oranges, yellows, reds) that it is simply too difficult to "eyeball" the best route. You have to, at some point, let the algorithm decide the route, especially since it has more fine-grained information than just the colors.
I ask myself when this issue comes up: what would I do with the extra info? I like to look at the map with all the traffic info, but I have never made a route decision by looking at the colors on the routes (google's or apple's). I used to let Waze, and now Apple Maps, decide on the best route. I may give it a quick check on Overview, but I largely trust it.
Using google maps for this was a moot point on iOS5 because we didn't have turn by turn.