Is an Android phone with audio GPS an acceptable substitute for a dedicated GPS system?

It should be good enough. Or you could get all crazy and spend the three bucks on a paper map.

A fiend of mine had a Garmin GPS that was stolen from his car only a month or so before he purchased a Droid X. He told me afterwards that he was almost glad that the old unit had been taken since the Droid worked so much better in certain ways.
Honestly, I think that there is no definitive answer to this question except your own opinion. You’d have to try it and see.
One advantage of the smartphone GPS over the dedicated unit is that you’ll be more inclined to take it with you when you leave the car, making it less likely to be stolen I suppose.

Yes. I haven’t seen a GPS unit do anything that my Droid’s Google Turn-by-Turn couldn’t do.
In fact, it’s one of the leading reasons for people to choose Droids over iPhones…

@koanhead It was a Magellan, but you are correct.

Yeah, there are a couple features of my old Roadmate that I miss, but there are many more features added, and the fact that I take it out and put it in my pocket every time I get out of the car greatly reduces the odds of me needing to replace my window again.

Yes, it has Google Navigation which is excellent. Also you can buy car mounts for the phone so it would be just like a GPS, you just might have to watch the battery life.

@asoccer345 Actually, without a car charger plugged in, it’ll blank out rather shortly just as it would if it were not in a dock. That is why I have the car charger as well (an actual Motorola brand one, not some $5 piece of crap that will burn out my battery (or phone!) by overcharging it!), not to mention that my normal commute is long enough to replenish most of the juice that I use in the 8–9 hours I am at work.

I plop my phone into the dock (which is already plugged into my lighter), plug in the headphone jack (which is hooked to my stereo) so I can listen to internet radio, MP3s, or hear the speakerphone, and away I go!