@leebee: Actually, what you need is a smartphone, which is different from a mere cell phone, which, I believe is still sold. So be careful. A plain old cell phone is just for making calls and sending texts. You need a smartphone, so you can download and use apps.
If you want to save some bucks, consider getting an Android phone and using a service like PureTalk, which is what I have. PureTalk doesn't have any contract and bills by the month. I'm paying about $24/month for unlimited calls and texts and far more than the data I ever use in a month, and that includes months where I spend 7 or 8 days at WDW.
PureTalk runs on the AT&T network, so I always have a good signal. But, depending on where you live, you might want to make sure that the service you get does in fact work well in your area.
There's absolutely no need to get an expensive iPhone and a superexpensive service plan. where you're locked into an entire year and the phone they're going to sell you for a supposed discount.
As far as apps go, it's extremely easy to download them and use them. Once you get past the first what-the-heck-am-I-supposed-to-do part of smartphone use, you'll be fine.