Pros
The drawbacks of working in a tech startup, and any startup, are generally related to short term risks. Pay isn't generally as good early on, benefits are limited until there are more employees, and the work life balance can be tenuous.
Cons
The first thing most people mention when you bring up startup culture is the work-life balance. Or in some cases, the lack of work-life balance. Startups are filled with people who are passionate about seeing a product or service come to life, and that usually entails long or odd hours. Culture has us believe people at startups ride scooters to their next meeting where they play foosball to brainstorm, but the reality is that startups require a level of dedication from each individual that you might not see at a corporation or big business.