Avantages
With IBM, there are certain resources that you will have access to: certain products, information, customers and clients, etc. Some people in the future may respond positively to you having IBM as an employer on your resume (but that may change as their reputation is tarnished). IBM is a patent leader. IBM owns certain products that you may have interest in developing, selling, supporting, etc.
Inconvénients
You will be happier somewhere else. There are plenty of employers that pay more. There are plenty that offer more of a chance to grow your career. There are many that will offer comparable benefits and name recognition. In the past, IBM urged their employees to complete at least two training classes each year to advance their skills. In the past IBM would recognize those whose contributions helped make the year a good one for the company. In the past, they offered the chance to advance in your pay band, move into other positions with the company, take advantage of the resources throughout the company. In the past, IBM's services competed by offering workers with greater skills that provided more knowledge and a better quality or service than others. In the past, IBM would continue to develop software and hardware lines with a long-tern strategy. None of that is true any longer. As an IBMer, you will see the only goal is short-term profits. You will see that quality is no longer mentioned, but cost always is. You will see that there is no chance to learn anything new. Smaller companies are acquired only to pad the portfolio of IBM's offerings, but they are not advanced, supported, or integrated with existing software/hardware. These things are sold until they need to upgrade, so another competitor is acquired. You will not get a raise. You will see the cost of your benefits rise while their value decreases. You will see people dumped from the company on a regular basis, and that will cause you such stress and concern over your future that you will become meek and frightened. You can learn this after working for IBM for years, or you can think about it before you even join the company.