International travel, while payed for, may nonetheless be tough for some people. I personally view this as a pro but it's important to consider.
Smaller companies tend to have less financial fat than larger corporations. Here is no different. Salaries tend to be a bit lower than larger groups could offer.
The lack of structure of a large firm could be hard for some people to work with. This is also widely viewed as a benefit by those who choose to work for a smaller company.
The firm is quite social and teams expect each other to be present and communicative. Someone who wants to regularly clock-in and clock-out without being overly present wouldn't fit well in the culture.