Instruct: Classify the given Amazon review into positive or negative sentiment.
Query: Battery back-up is a lie NO ALARM AT ALL WITH POWER FAILURE

I'd say the most basic feature in an alarm clock should be that it will still sound an alarm even if the power is out. That battery back-up feature is why I bought this clock. It says it has such a feature on the box, in the Amazon description, and in the customer reviews. HOWEVER - Read the battery door cover, the instructions, and you'll find the battery is for the clock memory only. I tested the unit to be sure. NO ALARM AT ALL WITH POWER FAILURE. Sure the alarm will sound as soon as the power is restored but who knows when that will be. Too me, that renders the clock worthless.