Google maps gives horrid directions. Also will only work when you have a data connection. And when you don’t is when you probably need the GPS the most. And they use their own maps which aren’t as thorough as a Naviteq or Tele Atlas application.
Haven’t given the new HTC navigator a fair shake and I doubt I will.
Others available in order of my preference as #1 being the most preferred for me:
1. Sygic (Aura)
2. Navigon
3. NDrive
4. CoPilot
5. Anything IGo
Many of these have free trials from the market. So give it a go and judge for yourself. Just reading the Description from it’s listing in the market will tell you everything about the app.