For some areas of the world this program may have some use. I purchased it as a supplement to cruising the N coast of Panama and Central America. At first I would have given the product a C but as it has gone through some upgrades and OS changes from Apple it is now worthless.
First, Navionics appears to require an almost constant internet connection either through a WiFi or phone network. While in Panama City I updated all the areas I was expecting to cruise. In the San Blas Islands there was no or very limited WiFi and the network is the slower GPRS or Edge. Somehow I lost the charts I had downloaded in Panama City. Not all, just some. Then trying to get them back on the GPRS network was as frustrating as pounding a 16 penny nail into cement. Besides that the program constantly told me that I should be on a faster 3g or WiFi network. Duh! Wouldn't that be nice. Except that the world isn't like that and not all countries have as easy access as downtown anywhere in the US.
Then with some of the charts I've downloaded the GPS on the iPad puts me in the middle of Land! (See the first image on the left) Good thing they have the "Warning" at the biginning of the program. In the warning should be the words "This program is only for practice and bears very little resemblance to the actual Earth!" Odd too that the topography appears quite good and accurate and can be placed on various hill tops correctly but they can't get the water shore line interface correct.
Then, in August of '12 I went to open the program and now all I had was a black screen with their icons. I can't even get a GPS marking on the chart because the chart is all black. I know the GPS works because I have another program that can read it and give me an accurate position. So unless you have $50 bucks to give away save it for something that works. I filled out one of Navionics feedback forms, received an automated reply and 3 weeks later still had not received a "real" answer. Several years later I still have not received an answer.
iNavionics Grade F