Thanks very much for your responses Tony and Cheryl.
Tony - You mention that "niche firms are often well regarded within the sectors they serve" - While the firm is a generalist strategy boutique it works on the basis of non-compete agreements and tailored solutions, with strong relationships from what I gathered. It is hard to pin down exactly what its "niche" may be apart from this.
During interviews, it was conveyed that most people who left the firm to go to industry ended up joining one of the firm's clients. This seems to tie in well with your suggestion that niche firms are regarded well in certain circles. It was also suggested that the firm has close links with Harvard and people currently pursuing an MBA there.
The biggest draw for me is that there is a lot of travel and cross staffing between international offices, which to me is an opportunity rahter than a disadvantage. There also seems to be high potential for earlier responsibility than the larger MBBB firms.
I don't wish to be a career consultant, and am looking at getting experience in the industry for some time while improving my CV, skill set and finding my preffered direction. My real interest lies within PE, industry and/or enterprise in the long term and I hope that this experience will help me prepare for this track.
Thanks a lot for your comments and any further advice would be fantastic. Also - if it isn't apparent till now, I decided to accept the offer.