Fantastic bag, keeps kitty safe and secure on my back. Went for a 3 hour train journey and she was absolutely fine. Much better than her usual bulky travel box, both for me and her. 4 stars because, for whatever reason, on the way back she was irritated and chewed some of the linining in the bag and made a slight rip/hole in the side, which I've since sewn up. Maybe produce future bags with a stronger material?
No problems regarding shoulder strap spacing, I'm not exactly what you'd call wide or broad shouldered, but I managed just fine using the middle strap which tightens both shoulder straps together and it worked perfectly fine.
On the whole, would defo recommend as a way to port kitty around!