In this part of the world, pretty much either traffic is not a factor, or if it is a factor, you have no alternate routes anyway.I still prefer to use a paper map and written directions when going somewhere new, but I will admit that traffic condition updates are really handy.
I like having paper maps as long as the scale is appropriate for what I'm doing. If you need street-level directions, the maps gets BIG. In SoCal, the Thomas Brothers was the standard, and the Lost Angeles County Thomas Brothers was nearly as thick as the telephone book. (Remember telephone books?)
Invariably, when I'm travelling somewhere new, I am driving into the sun, making it hard to make out the street signs. I've never understood how I manage this...
Out West, where the cities are generally newer, signage is much better. In the Philadelphia area we're blessed with streets that intersect at bizarre angles, streets that do not align across arteries, 5-point intersections, tiny "quaint" street signs, arbitrary one-way streets, and sections of roadway already obsolete in Benjamin Franklin's time.
So as much as I like to manage my own navigation and avoid becoming a 'child of the magenta line' I have come to love the GPS for actual navigation.
I'd never rely on it for trip planning tho.