Pros
I have had a couple jobs since Springhill, and this experience has allowed me to look back at Springhill pretty objectively. The best thing I can say about Springhill is that the projects are high-profile, and interesting. The last time I was interviewing, I was still citing examples of the work I did at Springhill. I can mention brand-name clients, and talk about high impact strategic work we guided them on. Especially rewarding is when you see the outcome of your hard work in an article about the company following your recommendations. Helps you know your work is making a difference for your clients. Additionally, the partners are really good guys. That's not to say they won't have high expectations (if you don't want a boss with high expectations, you're probably not destined for success anyway), but they are fair, and nice guys. I have worked for bad bosses, and can unequivocally say that working for good people is a huge plus.
Cons
As mentioned in other reviews, the hardest part is the primary research. This can include cold-calling. However, they are very upfront about this in the interviewing process, so I don't find it fair to interview for a job, be explained the parts of the job, then complain about what they told you they hired you to do. It's not for everyone, but if you have the right mentality, plenty of people thrive while doing it. Bottom Line: The job can be challenging. If you're up for the challenge, it is great experience, and personally helped me greatly in my career.