Pros
Lots of good training, support for taking CPA exams, large and interesting clients, pretty diverse employee pool, lots of women in management, lots of opportunity to learn new things and take responsibility for projects. I learned a lot about the industry and how life in public accounting works at this firm, both the good and the bad. I used to appreciate the benefits less than I do now that I work at another firm - they really weren't so bad. Had some fun chats with partners at firm parties.
Cons
Like any public accounting firm, they will take as much advantage of you as you allow them to. I had a couple bad experiences with specific people in management, but with a little distance, I can see that they were just being old school public accounting, and I was taking it too personally. It's never going to be an informal environment. As a lower level person, it's probably better to just check your personality at the door. Again, this is not specific to H&S, it's just how traditional public accounting is. Just like how two of the partners I saw on a daily basis refused to acknowledge my existence for the first year that I worked there, even though I said hello every day. Things worked out with them in the long run, but there is some funky formality that was a little hard to navigate as a newer staff.