Pros
Senior management is very involved and genuinely seems interested in employee's success. If you're on a good team it can be rewarding. Really depends on your team. MyRyan is good if your manager embraces it.
Cons
I found the culture to be very bizarre. The firm is obsessed with winning (seemingly meaningless) awards and people speak of Brint Ryan as if he is God. I'd get a constant barrage of e-mails asking me to fill out surveys for random awards and make contributions to the (quite conservative) Ryan Political Action Committee. Perhaps it is because I came from a very large firm, but the culture just was too weird for me. Aside from the culture, the only other cons I can think of is that your success really depends on your team and the review/compensation process could be better. If you're on a crappy team, it's not fun. Not all managers are equal and not all managers embrace MyRyan. Additionally, the review process is not entirely logical and can hamper your advancement and compensation until the next year. As an aside on compensation, I found Ryan's base salaries to be below market, but there is a high bonus potential. I left the firm for a very comparable position at a comparable firm with significantly higher base pay.