I love GPS navigation. I have had two GPS units that I used in my car, and found them very useful. The first one was a Tom Tom, which was easy to use and had great voice commands (even allowed you to use celebrity voices like John Cleese). Unfortunately, it had trouble hooking up to satellites, and that made it kind of frustrating to use. I traded it for a Garmin Nuvi, which was great at locking into satellites but the user-interface was non-intuitive and clumsy. Nevertheless, I very much appreciated having a GPS device with me when I was driving in unfamiliar territory.
When the iPhone 3G came out I was excited about the prospect of being able to use my iPhone to handle GPS chores. This was possible by using the Google Maps application. In practice, it was okay but not great. While walking it was fine, but the screen was too small to really use effectively while driving. It was something I could use to help someone else who was driving, but not very helpful if I was driving alone.
When Apple announced that Tom Tom would soon be developing a turn-by-turn application for the iPhone I was very excited. Having the iPhone announce turn-by-turn directions would be awesome! A few weeks ago I noticed that AT&T was offering turn-by-turn GPS on the iPhone for $10/month. This seemed like a ripoff, so I passed on trying that out. A friend of mine said he was using it. I asked him how it was, and he said it was okay. A few weeks later he told me that it was completely worthless.
Then, Navigon announced an iPhone app for $69 dollars (price goes up to $100 on August 15th). I read a great review of it so I decided to try it out. Around the city it seemed to work fine, which was a good sign. But last week I had a chance to take it on the road while I drove from New Orleans to Athens, GA to take my daughter back to school. I figured it would be a good test of how well the application works, and I found that it's a great application which I can heartily endorse.
The Navigon is a good deal right now ($69), and I doubt that the Tom Tom will be as cheap when it is finally released. It picks up the GPS signal pretty quickly and worked fine even when I kept it in the cup holder of my car (which is not optimal for picking up satellites). It doesn't come with a manual, but it's pretty easy to figure out (use it around your home town before heading out on an important trip). It has great graphics and works in portrait or landscape mode (also upside down in either mode).
It uses its own maps, which is good in that it doesn't require an internet connection as the Google Maps system does. But it also takes up 1.5 Gbs of space. It supposedly works with the iPhone 3G, as well as the 3GS (I tested it on a 3GS). It seems to have decent Point of Interests loaded in, and also remembers recently input locations. The best thing about it is the visual display that comes up when you reach a highway split. In other words, it shows you the actual highway signs, which makes it easy to see which split you should take (see example below which I screen captured during my recent trip).
Also, the voice commands are issued by a pleasing female voice. Just make sure your phone is not on 'silent mode' or you won't hear the commands. Oh, and if your phone rings you can take the call and not lose your GPS destination. You will have to relaunch the application, though, which brings me to…
The main thing that I didn't like was the fact that you can't keep the GPS going while you're on the phone. This means that you can't be on the phone if you are coming up on a tricky passage. I don't think that the Tom Tom will have this feature, since this is probably an issue about how iPhone applications run (e.g. only one can use the screen at a time).
Running the GPS for a long time will, of course, suck your battery life. So it's pretty much mandatory that you have it powered to the car charger while you're driving. On the way to the airport in Atlanta (where I was going to drop off the rental car and then fly back to New Orleans), I accidentally knocked the power charger and failed to notice that the battery was draining. Not good. So, you not only have to plug it in, but also make sure that it stays plugged in!
If you are going to use this application for a long time I recommend that you get the Kensington car mount ($24) to hold the phone in place for easy viewing. I was skeptical about whether the Kensington car mount would work well. No doubts anymore. It rocks!
One reviewer of the Navigon complained that, while the application allowed you to locate nearby POI's (points of interest) and their phone numbers, it wouldn't allow you to dial the place from within the application. I'm not so dismayed by that, but I suppose it would be nice.
The last thing that annoyed me, and this is something you can tweak, is that the default was set to repeatedly ding whenever I exceeded the highway speed by 10 miles per hour. Make sure you tweak these settings before you get on the road because trying to adjust them while you're driving will be frustrating (and unsafe).
The Navigon exceeded my expectations. I love not having to carry a separate GPS unit with me when I travel (of course I will be packing the Kensington car mount). The iPhone GPS is apparently robust enough to make this work pretty well. I have not tested it in rural locations, so I don't know how it would work there. But since all the maps are stored on the iPhone I presume it will work in locations where the iPhone doesn't get a signal. Obviously, the GPS needs a signal to work, but the GPS signal is not directly dependent on the cellphone signal so it should work as well as any other GPS device would.
But remember, it takes up 1.5 GBs of space so make sure you have enough space on your iPhone before you download it.