I have a garmin GPS. Its o.k

I've found that in the places like New York city, when im going through bridges or tunnels etc, I loose reception, and then im stuck guessing which exit to take next. By having google maps on my iphone, wth step by step directions, im not to concerned with losingconnections etc.

Before I bought my own, I would rent one with my car rental, and most of the time, the maps were out of date and took me to nowhere.

So it is helpful, but it can be a pain when you need to have the most updated map uploaded onto the device.