The reviews for this new model are good, and the older version has lots of good reviews too.
Look through the Amazon listing and it's clear English isn't their first language, lots of mistakes, as is typical of these sorts of listings.
15hrs is for the lowest power level and they stress you need to charge up at least 5 hours to get that. Battery decay will surely cut the time significantly as you use 'em - just like your phone.
For my rides, I certainly do not need "All Day" heat! If it lasts a couple hours, I will be very happy. Much more important that I can change temps without taking the glove off, waterproof, rechargeable, touchscreen capable. The other thing I really liked is that they are not wired into the slingshot's electric system!
I thought about Milwaukee gloves with similar specs for $200+, but they are made in the same factories no doubt!
I'll let you know how these do.