I didn't like the first Garmin StreetPilot app for iOS because maps had to be downloaded on the fly. Not good if you are out of cellular range, and even worse if you you are downloading lots of maps on a metered data plan.
Garmin has finally come around and is offering maps that are contained on your iPhone. There are two US versions, one with the 49 states (Alaska is excluded) and and some Caribbean islands for US $39.99 and a North America version for $49.99. There is also a UK and Ireland version for £44.99.
Of course these new apps are a larger download. The US version is 1.37 GB while the original StreetPilot app weighed in at 10 MB. This latest version makes for a far more competitive offering on the iPhone. I'm hoping to get a copy for review.