While BTech prepares you with the basic knowledge of technical subjects, MTech helps you get a better insight into subjects you develop a keener interest in. By this time, you are mature enough to expand your horizons.
An MTech degree adds value to your education and gives you an edge over the others. You are enriched knowledge wise and skill wise as you choose to specialize in the core subjects. Your practical knowledge, expanded skill set and on field experience will make you stand out and help you to advance in your career.
Moreover, you will get to meet people with technical bend of mind, people who might be on the same path as yours. Such encounters often lead to great accomplishments in the future.