Stressful - working with deadlines, many different people, projects, and in a small company (i.e. multiple hats to wear) means there is plenty that one can be stressed from; you have to be humble and welcome the opportunity to grow if you want to be successful here;
High Expectations - in this smaller environment your work is more visible (which is great if you work hard) so you have to stay on your toes, communicate and collaborate more than some are comfortable with;