Foreflight is a well designed, full featured flight planning, weather gathering, and chart viewing application. I've used it on my iPad and iPhone for two years. There are other good competitors out there too - WingX and the new Garmin App come to mind. Foreflight is the market leader and seems a bit more polished than WingX. I have not tried the Garmin App.
The yearly cost of the chart subscriptions is quite a bit less than you would end up paying for just a small set of coverage on paper charts. The ability to have VFR and IFR charts easily downloaded to your IOS device every 28 or 56 days is great.
If you have both an iPad and iPhone, one subscription covers both devices. The iPhone, while smaller, makes an excellent backup to the iPad when in flight. I stopped carrying paper charts a year ago.