I use this to run my FT-891 on 50 watts when I'm packing it in to an activation zone. It's half the size/weight of the 12AH so makes it a lot easier to haul the whole setup into remote locations. It easily powers the radio at 50 watt power level until I'm bored with operating the radio, so it's large enough. I haven't run this battery to empty yet, but my guess is it would probably run my setup for around 4 hours.
I like the form factor. The battery has been reliable so far. It's super lightweight compared to a SLAB. I honestly have a hard time believing how much power I can get out of something this lightweight. That fact that it's only 30 bucks seems almost impossible.
The battery arrived within a couple of days. Customer service has been excellent. When a different battery I had ordered a couple months ago was out of stock, they promptly informed me by email and issued a refund. I've had good experiences with this company and I recommend their products.