I shared until I was 13. It had good things and bad things. My older sister snored

and my younger sister was so messy

but I got on alright with my brother (4 yrs younger) most of the time. We just got rotated around so we shared with someone else when we got sick of each other. I think it was good for me, and I would like to make my kids share when they are little, whether i need to or not. DH is not so sure, as he never shared a room.
Just my 2 cents worth, anyway.