I’ve got a Deuter Race X which is that size and I rate it. The 10L is the pack (not belt pockets/odd compartments) and internally it has almost everything in the one big ‘backpack’ bit, with a small internal mesh pocket (which when I ride with it holds my multitool, levers and mini pump). Takes a 2L hydro bag too. Mesh side pockets, two small zippered external pockets (one on top – mobile phone, keys, small first aid kit; and one facing backwards).
Is splashproof and has an integral hi-viz raincover (held in small zippered pocket on the bottom).
Mesh shoulder straps tighten up nice and snug against shoulders, chest- and waist-level clips to hold in situ while moving. Suits me v. well and carries everything I need on day-long rides with no saddle- (or other) bag.