Pros
For a huge agency, Weber Shandwick offers personalized attention from middle management, insanely fun team bonding events and the opportunity to grow in the direction you want. My boss saw that I had an interest in financial services, and made an effort to move me to those accounts. Despite what comes with a big agency (bureaucracy, etc.), the corporate culture is energizing and fresh. People are smart and cool. In fact, some of my best friends I met at work. The fish in the lobby are adorable and we made up names for them (Big Poppa is the fat one who eats the others' food. If you come, you'll see him). I got the opportunity to manage the interns this summer, which was great experience in a supervisory role. The company also offers tons of training via lunch and learns and "classes" you can take on topics ranging from time management to communication styles.
Cons
Working on the same clients for the entirety of your job can get a little tiresome -- I get bored of clients after about a year and a half. Luckily, my managers were really supportive of my curiosity and desire to try new things. Sometimes it can feel like you're working on the same projects again and again, so it's up to you to volunteer for out-of-the-box assignments. If you do, management is really supportive, but the onus is on you.