Don - I know you have been searching around on the net so you might have found this already, but they seem to explain it pretty well...
http://www.hotslots132.com/digitalslotcars.php
Unfortunately I have never run a digital set,so don't know whether they are good or bad. The one thing that is mentioned in the page above is the simplicity of a slot car and how the digital system deviates from this a little. One of the nicest things when I was a kid is that I could fix my own cars easily.
In fact, some of the most fun cars I have run on my track are some old Scalextric Formula Juniors. Of course I'm going back on what I said about open wheel cars, but these are fun for experienced drivers. They aren't very fast at all, but they have very skinny tires, very low weight, and consequently hardly any grip. Combine that with a guide pin instead of a blade which makes complete spins fairly frequent, and you get some realy fun racing.
I guess you're going to have to find a local hobby shop with a set and go and play!