I've been testing it out as far as I can do in the U.S without spending any money.
So far, it works as advertised. Inbound calls ring and outbound calls receive a ring back relatively quickly. Inbound text messages get delivered quickly. I particularly like that there are several methods to set up and listen to voicemail without spending any money. And one of the best features is the email-to-sms gateway that allows anyone to send me a text using email, with no cost to receive.
Obviously the real test will be later, when I'm traveling.