Hmmm, im a bit iffy about it. If someone borrowed my notes that I had worked painstakingly at making than i would be really, really pissed off.
But on the other hand I find myself using the BoS notes that people have submitted. I dont use them straight out, I use them as well as my own classnotes, textbooks and excel study guides to make my syllabus summaries, so the notes serve as a resource rather than something that I am using directly.
I think the benifit is greater when you make you own, because through going through the process of searching for the correct information, summarising it, writing it down etc, you are more likely to remember it.
Anyway, personally I think it is wrong to just use somones notes, but if you use them as a guide in making your own notes it is fine. It depends on your own moral standards, this is just my belief. Its not a huge issue to me (unless you wanna borrow mine lol) and if you dont think it is wrong I wont consider you having low moral standards or anything.
Just think to yourself, how would you feel if you were the person whose study notes someone was using? Would you feel cheated or would you be fine with it?