Hmmm.... if you are going to use it as a "chart", why not just use the chart?? What does the iPad do that your Garmin doesn't already do? Admittantly, I'm not up on the capacities of the iPad for aviation use, just never saw the need for VFR flight. I can see where it would be useful IFR.
Gary,
Quite a few things - While I'm instrument rated and travel a lot, I generally fly VFR unless weather or operations (ie this past weekend's trip into the SFRA) dictates otherwise.
Here's a few things that ForeFlight does that are helpful to the VFR-only pilot and beat the heck out of charts:
1) You always have current charts, even if the new ones come out when you're away from home and at a tiny airport that doesn't sell 'em. It's a helluva lot easier to find an internet connection than an FBO that sells charts these days. You can also get any chart you need.
2) It not only replaces charts, it replaces A/FD's and basically all the other paper in the cockpit. You can use additional apps for checklists, GPS flight tracking (ie get the track after the flight), and numerous other things. In fact, there are many uses for it on the ground after you reach your destination too - A quick check on what the weather's doing, a map to get around in the courtesy car, etc.
3) Flight planning and weather briefings - No more calls to LockMart. You can file a flight plan (and get verification that it was actually filed), get an official DUATS briefing that's split into its various sections to be easier to read, get lots of different weather maps, plan your flight via typing in waypoints on the keyboard or by tapping spots on the chart, and then see what the weather is like relative to where you're flying by showing over a dozen different weather map products right on the chart with your route showing. (example - you can get a map showing the ceiling, visibility, wind, etc. from the latest METAR right on the chart.)
4) It costs about $40/year just to keep one sectional and one A/FD up to date. ForeFlight is $75/year for the entire US. If you go anywhere, it'll pay for itself in a hurry! (Between ForeFlight and books, my iPad paid for itself in a little over a year. And yes, I mean the iPad itself, not just the FF subscription.)
I'm sure you'll find more - It's a great tool, and pretty fun for planning fantasy flights as well!