Has anyone used Magicjack? Is it any good?

My sister based in the US send our mother that Magicjack with phone. You see our mother is not comfortable operating a PC but with it she can call/receive call just like a regular phone. Its basically like Yahoo Messenger and the phone simplify its operation. Its a lot cheaper than long distance calls because the charges are for local calls. But if your comfortable using a PC then an internet messenger will do the same for free. Both may I add requires a PC(Win XP sp0, sp1 or sp2 but not sp3) and an internet connection.