We hooked up Ooma this weekend.  It works great!  There is no loss of quality in our phone calls, I was able to easily do a three-way conference, the voicemail works, and you can listen to the messages via the Ooma Lounge, which will be handy when we are traveling.  I even inadvertently enabled the DND (Do Not Disturb) feature and the next call went straight to voicemail.  XD

If we continue to be happy with it, we'll be dumping AT&T in favor of a lifetime of free (or cheap, if we continue with the Premier Services) phone service.  We currently spend $36.95 per month for a single phone line + Caller ID and Call Waiting.  All that comes free with Ooma for the initial outlay of $200.  In other words, it pays for itself in less than six months.  Six months!  If we stick with Premier, it means we save $343 per year (assuming rates change on neither side).

The only other equipment I'm going to add to the mix is an uninterruptible power supply to insure we have phone service when the power goes out.