Here are some quick thoughts on the igomyway app. Street names are extremely easy to read (important to me). Three views 3D+, 3D and 2D. 3D+ is interesting with elevation changes and 3d buildings. Routing is extremely quick. GPS signal locks right away. I did notice a slight lag on the 3d maps, but not enought ot cause any problems. I think this is a iphone issue as it seems all the gps turn by turn apps lag. Spoken street names are coming in an update. The thing I like best, is the app is so finger friendly. It is an amazing interface that is simple to use when in the car.
I purchased a navigon in car gps unit about 6 months ago and returned it after a few days. I thought the routing was terrible and the map graphics were hard to read including street names. I'm assuming this is the same maps and routing engine that is on the iphone. Navigon, quicly pulled out of the north american car gps units a few months later.
http://www.pcmag.com/article2/0,2817,2346414,00.asp