Just as Jon Arnold reports that he likes Ooma, another Jon, Jonathan Greene at atmaspheric | endeavors complains about several annoyances including: "an audible buzzing background sound [that makes] it very difficult to hear the other party" and issues with outbound caller ID (the Caller ID the person he calls sees).
CallerID is apparently hidden for “Security Reasons” by default, but you can enable it on outgoing calls by dialing *82. I expressed my discontent with this option and suggested it be a one time activation with the option to block as needed - the way everyone else handles it.
Jon Arnold, on the other hand, says:
Ooma works, and I think it's a well designed product. That's the easy part in my mind. Getting this to market and convincing people to spend this kind of money upfront from an unknown company will be the real challenge in my mind. Right now, Oooma is very Voice 1.0
We should note that neither person actually paid the $400 for their Ooma box - they got it free as a beta tester.