We've had something similar in Australia on Telstra for a while now. It's called a T-hub and comes with a base station which is a fully usable android tablet as-well.
Not that I own one.
I'd correct one part. Dealing with a power outage is very simple, you just use your UPS. It's happened to me more than a few times, and this thing takes next to no power.
POTS is still the most reliable, but one good thing about Ooma is, even if your phone is down, people can still leave you messages that you can retrieve when it comes back up.
I have owned the regular Ooma for 2 years. Unfortunately I signed up about 2 months after they grandfathered in the other users with absolutly no tax at all. I pay about 3 bucks a month and have had absolutely no problems at all. It has gone out briefly 1 or 2 times when my network was down, but my previous phone probably did that just as much. Probably one of the smartest things I ever did.
Ou reviewer of the Linx has lived with Ooma for almost three years, he's pretty enthusiastic about the Linx: http://intheboombox.tv/ooma-linx-a-real-jack-in-the-box-voip-telephone-product-review/
I had it up and running in not time - just connect it to your router and plug in your phone. Ooma support walked me through the setup. Their support is great - online chat answers my questions fast. This is a must for saving money. A great product.