I've used mine in WDW but as with other phones it is sometimes hard to find the sweet spot to get good reception in the parks. You can also call and add minutes to your phone if you need to.
I have heard others solve the roaming issue with these phones by changing their home area to WDW while on vacation and then switching back when they return home. I think you can change your area a couple of times a year without a problem. I've never done this because I don't use my cell on vacation unless it's an emergency.