Prós
After 2 years at a larger firm I didn't think it was possible to work in pharma/management consulting and also have fun, but at ISA it is. The environment is supportive and collaborative, not at all competitive. My colleagues at ISA are not just intelligent and talented, but also genuinely interested in healthcare and the trends affecting our industry. The firm culture very much embodies the "work hard, play hard" dynamic- it is a great place to grow and learn professionally while not dreading coming in to work every day.
In stark contrast to a bigger firm, your ideas are heard and acted on by senior management. You are also able to take on increased roles and responsibilities as soon as you are ready, willing, and able. If the internal politics and unnecessary restrictiveness of a larger consultancy sound frustrating ISA will be a refreshing change of pace. Travel is also generally limited to kickoffs and final presentations so work-life balance is greatly improved from the typical M-Th on site consulting model.
Contras
If i had to pinpoint one thing it would be working at a smaller firm limits the number of paid databases and report resources you have access to but if you are even moderately good at secondary research this isn't a big issue.