I've been using Telenav with Nextel since it first came out. It has always worked great. Recently I moved over to Sprint so that I can get the 8703e and I have say that this version of Telenav is awesome. Works great where ever I am and the 3d maps that it shows now are great. No complaints. I'm on the road everyday and it is very reliable and has saved tremendous time.
I can't say anything bad or good about other GPS devices because I have never felt the need to get them. I like my all in one package.
I use Telenav with my 8703e and it works well. It takes at most 30 seconds to find you and track the route after submitting the address. The volume could be louder, but the graphics are great and it has pulled me out of a jam several times now.