A little pricey, but great value
I was hesitant, at first, to purchase this (the 6.5L version) as I thought the volume to cost ratio was a little high. Since using this for a while, though, I've really come to love using this bag. The size is spot-on for carrying all sorts of things you may want to take with you on short outings, such as a camera, repair kit, raincoat, a secure place to keep bike lights and reflective clothing…it's just the right size for many things.
Living in a Tropical environment, though, be careful about keeping electronic devices under the transparent cover during the heat of the day. Although it has internal vents, the direct sunlight on the plastic and device may lead to overheating and potentially dangerous issues with lithium batteries. I pop my phone under the transparent cover when riding to work in the early morning or in shaded forest environments, but will keep it inside the bag during exposed daylight rides.
The immediate convenience of the bag, before, after and during a ride is undeniably nifty and it saves me from having to put on a backpack on short outings.
Riding a gravel bike, I don't really have the space to attach drink bottle holders to the attached bottle holder brackets on the sides as the handle bars sit fairly close to the sides of the bag. I'm considering experimenting with tying a sturdy elastic or rubber band between the brackets to possibly suspend other lightweight things to the front and outside of the bag, instead.
One more important consideration you will need to make is that the bag will interfere with the spread and beam of a handlebar-mounted front light, if you ride during darker hours. I have raised my light using a clamp and arm that I had from other pursuits, but I'm not aware of any ready-to-go, elevated light mounts that are commercially available. You may need to get inventive, on this front.
Anyway, I have been pleasantly convinced that this was a worthwhile investment for my intended use of the bag, and my initial concerns have been outweighed by the unexpected benefits, overall.