I got a Nuvi 650 GPS device. It's pretty cool. It works pretty much out of the box. The screen is nice 4" x 3", it's color and fairly big. The voice is fine but I don't have any place to stick the device unless I mount it on the windshield (luckily I have a little compartment that I can use for it where the GPS device for the car was supposed to be).
I recommend it overall and definitely over the other 600 series — it has the wide color screen with the least features so the least expensive of the bunch. I'm sure the devices will get even bigger but this one is large enough and the voice is loud. I haven't explored the other features, there might be too many. This device gets the basics right — map, directions, places of interest — so that's all I really need.
I would wait until it gets down to like $250 – $300 though if it ever gets there.