I've been using them for the past month and a half or so. It's maps, provided by NAVTEQ, are some of the best online maps I've seen yet. They are not 100% accurate but compared to MapQuest they are great. I know MapQuest is the current leader, but a lot of that has to do with market dominance and age (it was one of the first) more than quality.
Like I said the maps aren't 100% accurate but reading the maps is much easier. The street names are clearly marked and major roads are highlighted for your ease. The problems I've noticed are related to recent road construction. Nashville is always changing something, it seems. It's difficult to keep up with that. I'm sure this'll be a problem with any mapping software out there however. The second problem I noticed was that when I put my address into the system it found my house about 2 houses down from where it's actually located. It put me on the corner rather than up the hill. That's not too bad though. A few hundred feet off target is reasonable to me.
Another addition that Google added was the satellite maps. You can zoom to your house and then click a link to see the satellite map. It's pretty cool. Not all areas can zoom in very close but some can. Depends on how far out you are from a major metropolitan area.
So next time you are looking for directions, give Google Maps a chance. I bet you'll like it.