Pros
Fierce is a well-run, aggressively managed company that seems to be able to dominate any niche it shoots for. It offers great jobs for sharp young minds that are ready to move at a fast pace and be challenged. It also has an excellent reputation in the marketplace, which helps grease the wheels when doing business.
Cons
When I was there, I served under the company's founder, who though capricious and confrontational at times, was very good at steering the ship and creating a reasonably pleasant atmosphere. But once he sold the company to a VC firm and existed, things got tense and managers increasingly petty. Also, at least when I was there, combined sick AND vacation time was only two weeks in total (though the health plan was good). Also, on a personal note, I believe I accomplished a great deal for the company, but advancement seemed to be out of the question.