Fast pace learning, good exposure to the newbie to gain experience and lot of senior can teach from zero. But mostly senior not have much time to spare due to tons of work.
Cons
The more experienced and knowledgeable you become, the more responsibilities the company places on you. No work life balance. Eventually, you're expected to work independently, yet the salary often remains disproportionate to the responsibilities you carry. HR is very toxic and have huge political issues.