To properly review Ooma, you have to consider the two levels of service. I got a one year subscription to Premier to get the free wireless dongle. The wireless hardware is perfect. I can plug my phone in anywhere, and get crystal clear audio in my calls. It frees the phone from being stuck next to the router, and they may be the only residential provider that lets you do that.
The actual premier service has a number of features that I could take or leave, like caller ID with name, and the instant second line. I don't need a second line, and Ooma lets you add numbers to your contact list. What I was most curious about was the black list and the ability to subscribe to do-not-call lists. It turned out that I get no more or fewer unwanted calls. So, I expected to have a year of blessed silence, and I ended up paying much more attention to unwanted calls than if I had simply ignored them and forgotten about it.
As a basic service, Ooma simply cannot be outdone. I pay only taxes, which is less than $4 per month. Compared to paying $30 for cable company VoIP, or even more for traditional service, I'm saving money every day. As a long-term investment, the longer I own it, the happier I am.
Finally, as a note to anyone who thinks that VoIP may be unreliable, I ask you--do you use a 1980's phone with a long curly cable? If you're anything like me, you use a wireless phone. If the power goes out, you wouldn't be able to use your phone anyway. Ooma also has failover, so if your internet is out, the call just rings your cell phone. It's more reliable than other phone options.