Pros
Flexibility to work off-site and from home, with a good work-life balance (generally no more than 50 hours/week). Smaller practices and lines of business make it easier to get to know senior management. Everyone generally has an open door policy and senior managers are easy to approach. Company is growing with a variety of new opportunities, particularly good if you are interested in consulting for the public sector.
Cons
Focus is primarily on the federal government, so if you're looking to get into consulting for the commercial sector, ICF is not the best bet unless you have a focus on the energy industry. Company is growing, so strategic direction, communication, priorities, and expectations are not always clear. Management's focus is very heavy on employee utilization, making it difficult to maintain a "bench", focus on developing offerings, and growing business. Pooir internal communication and information sharing about the full range of offerings and capabilities within the company, making it difficult to cross-sell or to tap into specific areas of expertise quickly, so sometimes feels like you're reinventing the wheel on projects.