I had the unfortunate chance to test this last night during a tornado warning, so I have a chance to give a fully-objective review of it now.
First of all, what it's not:
- It does not replace a good NOAA Weather Radio, and you still want a good NOAA Weather Radio to wake you up for an actual Tornado Warning
- It does not replace radar. You still need to be looking at radar, especially SRV, to track where a tornado is actually headed.
With that said, here's where I've found it to be useful:
Last night, it was overall quiet outside, then my TA went off with a "Severe Storm" nearby alert. So I ran to my office and fired up radar. Sure enough, there were a couple of thunderstorm cells nearby, and we received the thunderstorms with hail. I didn't think the storms would be "that" intense, so I signed off my computer and was getting ready for bed.
Then the TA went off again with the "Tornado Likely" message. I was on my way back to my office to fire up my computer/radar again, when we were officially put under a Tornado Warning, so I took cover and tracked on my iPad during the storm.
Plus our power went out during the storm, and since I wasn't hanging on my phone to conserve battery, the TA would chime when the storm was severe enough that I needed to actually spend time firing up my phone and using battery on it.
A replacement from radar or a NOAA weather radio? Absolutely not. Is it a useful "extra layer" to "get my attention" before a major weather event that I need to be more "weather aware" and monitoring radar and NOAA Weather Radio? Yes. Plus it works as a decent Lightning detection backup if my power/Internet is out and my lightning sensor is down (and I'm conserving battery on my iPhone)
Overall, it was worth the money. It's not "magical", and I wouldn't over-hype it, but used responsibly, it's a useful "extra layer" alerter in my toolbox.