Pros
Ryan is a great place to start your career. They train you very well, and you will certainly know whatever practice area you're hired into very, very well. They also provide wonderful soft skill training classes as well. The work is interesting and ever-changing, which is nice. The benefits are nice and fairly comparable to others in the same sector. The flex environment provides the opportunity to really balance out your professional and personal life as long as you have a manager willing to allow you to take advantage of it.
Cons
While there, you will feel like you are preparing yourself for many more opportunities. This is untrue - you will find that unless you are in a specialty tax practice (severance, motor fuels, property, etc.), the daily activities and tasks you become very proficient at are not really especially desirable to anyone other than other consulting firms (unless you plan to be at Ryan for many years). There is no compliance work, no strategic planning, or any other of the many requirements that you will find when/if you start looking to move on from Ryan. Moving from one tax practice to another is difficult and practically unheard of - if you are hired into the Sales and Use Practice, do not expect to be able to easily move to Property Tax or Severance Tax. The bonus structure is biased and unfair. Unless you are on one of the "rockstar" teams (it usually ends up that the same 10-15 teams are making the most revenue each and every year), you will not be making the additional salary that Ryan likes to say that everyone in the firm is making. Also, Ryan has become very slow to promote to a management level (expect it to take 8-10 years). Additionally, the raise cycle is inconsistent and difficult (not the average annual pay increase that is fairly common at other firms). The flex work environment that Ryan has is difficult to navigate at best. As long as you have a manager that is willing to allow you to use it, it's great. However, it can be very frustrating when you are made to feel guilty/punished when taking time off. Not having a set amount of PTO days makes taking vacation near impossible. You will never truly be off, you will be expected to answer emails and phone calls while on vacation regardless. Also, working from home is not as common as they would make it to be - lots of the managers still feel that if you are not in the office, you are not actually working. Expect to be in the office on a consistent basis and expect to put in as many hours as anyone working at the Big Four (expect 50-60+ hours a week).