We had a ~4 hour power outage last year and it kept my tank running with about 1/3 drain on the battery (i bought it because in a previous power outage, i lost about $1k in coral).
But we've also used it fishing, camping, and one of my favorite usages is just plugging in some lamps when my wife insists I replace some random light fixture and it is dark outside (and have to turn off the breaker for that room 🙂 ).
At some point I'll buy a bigger one... but honestly, with the 110w solar panels and a 2 of the 245Wh banks, i can keep our computers and phones charged indefinitely in a power outage 🙂
Our power hardly goes out... but if it did, I would definitely buy one of the bigger ones (lots of youtube reviews show them running fridges and other appliances).