I'm a pretty versatile biker. I'll do anything from rides with 3500' of climbing, a couple Crest shuttles in a day, playing in Moab or lapping Canyons. And I seriously love this pack, it works really well for all of that. The main compartment is the only thing I'd change, it's just a single pocket and it has no kind of dividers or subpockets or anything. I throw a bunch of supplies in there, and it just kinda sucks not being able to organize it at all. Trying to quickly dig to the bottom to get something can be annoying. But that's the only complaint, everything else is awesome. The ingenious stuff like the fold out tool pouch and the magnet on the valve are super convenient. The foam on the back is nice and minimizes sweating there, and the straps are comfortable and forget I'm wearing the pack most of the time. The lidlock works just as it should, and the outer pocket holds a pair of kneepads perfectly.
I'd definitely recommend the pack for any all-mountain/enduro type riders. Big enough to hold all the necessities, but light and comfortable enough to not be noticeable on the long ups or the rowdy downs.