Pros
Amazingly smart people who are passionate about the work they do. The talent and out-of-the-box thinking is what makes Allen's product a solid one. However...
Cons
(1) No onboarding program exists. If you want to be initiated by fire and water hose, Allen's your place.
(2) Poor leadership and lack of vision. If you want to know how you fit into the bigger picture and how your contributions make a difference, do not expect leadership to provide insight or guidance. You need to learn how to work in severe ambiguity.
(3) Poor project management. Don't expect to have a life if you work for Allen. Consistent expectations that you will have to "burn the midnight oil" to meet unrealistic project timelines. If you want work-life balance, Allen is probably not the place you will want to work.
(4) Low wage. Allen pays most employees below market, whereas other employees are overpaid based on favoritism. If you are seeking a salary / hourly rate that is commensurate with your experience, you will be disappointed.