IMHO, I think being an SO falls somewhere between dozing for dollars and the greatest learning experience in aviation. Yes, you learn a lot but you've got to be willing to pick the guy's brains who are in the front seats. In my company, you had to be out of the control seats below transition so that kind of hinders your learning. So, you're in the control seats in cruise and the higher parts of climb and descent. You don't want to be too busy dozing if you have an engine fire or maybe a depressurisation! For departure and arrival, you're keeping a keen eye on the 2 guys in the control seats. If they miss something and you don't pick it up, what were you doing? Just enjoying the view?
My best learning experience so far? Getting out of the back seat and into the righthand seat!