hi all! as you know, i bought the napa spring bag in dark chocolate brown...i haven't started to use it yet and have a couple of questions for those of you who own one...is the leather durable? i love the bag, and am concerned about how durable the leather is...it fits a TON of my stuff which is great! do any of you use the shoulder strap? it's pretty narrow, i think...would love any thoughts from those of you who have this bag! thanks!