[GPSNavX]

I would compare the Navionics app (and most of the other marine chart apps) this way. They are good chart viewers with important meta data, but do not provide much information for real-time navigation or an interface to external real-time instrumentation.

However, the good thing with iOS is it makes it very easy to switch between and run multiple apps. All can share the "Location Services" on the iPhone/iPad. None of the marine apps including iNavX cost a fortune. No reason not to have several as no one app is the end all solution.

The latest version of the Navionics app on iPad seems to be a bit buggy as I can't keep it running for more than a few minutes before it crashes. Others have reported the same in the app reviews and on Facebook. I am confident Navionics will address these issues in a future release.

Here is how I see iNavX different then some of the others ..

Access the largest library of up to date official charts and maps
Comprehensive route and waypoint management and navigation
Import/Export of waypoints, routes and tracks in both KML and GPX format
GRIB Weather overlay (wind, pressure, waves, precipitation rate and temperature)
Anchor alarm
True and Magnetic bearings
Great circle computation for all bearings and distance
NMEA-0183 display via TCP/IP
AIS target display
Digital compass
Instrument display
Chart and route printing
Chart emailing
Course Up chart orientation
Full screen display
Runs on both iPad and iPhone

Again I recommend one not limit themselves to any one app.

p.s. A one or two star rating is for an app "You hate". I interpret that to mean an app that provides no value. One that I would delete off of my iPhone/iPad.