Love it! The field is in high demand all over the world. It's also the highest paid area of psychology, with salaries averaging ~$20 000 per year higher than the next highest paid area of Psychology.
Broadly, I/O Psychology is the science of applying psychological principles to the workplace. How I/O differs from other areas of Psychology is that we solve personnel problems rather than personal problem. Our mandate is to make healthy people happier and more productive.
People on the "I" side of I/O Psychology focus on benefitting employers (e.g., design employee selection systems, training systems, compensation system). People on the "O" side focus on benefiting employees (e.g., designing jobs to be more rewarding, studying teamwork, leadership development, employee satisfaction, employee engagement, facilitating mergers and acquisitions).
Some I/O Psychologists become professors at universities. Most are practitioners working as either (1) independent consultants for businesses, (2) government employees, or (3) in-house consultants for a particular business (e.g., Google). Most consulting work focuses around employee selection and/or leadership development.
My own career path was very direct: after completing my Masters in I/O Psychology, I was hired by a test publishing firm while completing my Ph.D. I worked at the test publisher for 5 years. Although I could happily have stayed much longer, Sokanu made an offer I couldn't refuse. So here I am!
I work at the training area and it's very good to see the results of the job, people really learning and doing their work better. In the other hand, there's a lot of pressure for results, little autonomy to make decisions, little flexibility and long hours.
I don't enjoy selling, which can be a large part of this field. I do enjoy research and statistical analysis, which can also be a large part of the field. So far most of my experience has been with the former. If I could start over in college, I'd probably go into biology or geography instead.