"I am 27 years old and have just finished law school and passed the state bar examination. Now I am ready to begin my new career as a lawyer. I am not interested in a job with a big firm. I’d like to be more on my own. I have two friends who are in similar situations. But it takes money to start a law practice. A modern law firm needs a lot of business machines—computers, copiers, fax machines, and so on. Even in a small firm the lawyers might need to hire some helpers—a receptionist, maybe a paralegal worker. I want this firm to be a success, but I am not sure I have all the legal and business skills I need to pull it off." What are the advantages and disadvantages of starting own business?

Flexibility: a person who starts his own business does not necessarily have to work 9/5 monday-friday, he can set his own schedule. Needless to say, many business owners work longer hours than regular employees, but the do so because of the hope to earn more money from profits than from a regular wage.
The possibility of profit: an employee in a legal firm will not be able to obtain any dividends (unless he owns stock), while the very definition of a business owner is someone who obtains profits.
Fulfillment: it is probably more fulfilling to see your own business develop and grow than go to work everyday for someone else's company.

Some disdavantages are:

Risk: starting a business is risky. The business might result in losses instead of profits, in other words, the business may fail.
Capital needs: to start a business, you need some capital, and it is not always easy to obtain. Most business owners either get debts, or liquidate some of their own assets (house, car, etc) to finance the company.
Longer work hours: as stated above, it's very likely that a business owner will have to work night and day, especially during the first stages.