That's a nice looking bit of kit, I'd estimate that as having a ~20L capacity. Bit small for my needs, but if you can cut down what you carry with you, then great. The warranty isn't great though - 6 months!
My last daysack was a Tripp, which I think is an own-brand for Debenhams. It was okay but lasted, if my poor memory serves, around 18 months, maybe a couple of years. I'd already had a seam repaired, and a couple of zips had fallen off, and finally the main compartment plastic zip started losing teeth and it would not close reliably. I think it was £60ish.
Of course, I could buy a cheap one every year, but the point of my trying a much more expensive one this time around is to see if I can get a bag that lasts ~4+ years. I throw away too much disposable stuff away as it is.