Its one of the oldest branch of engineering. One of the appealing feature is that the field is broad and diverse. All in all mechanical engineering offers a wide bouquet of job options to students who are looking for a stable and stimulating career. The most important fields in Mechanical Engineering are:
Structural Engineering
Petroleum Engineering
Mining Engineering
CFD,CAE. etc
Aerospace Engineering
Mechanical Engineers get decent jobs in automobile industry, space research, energy, aeronautical, air conditioning, medical industry, turbine manufacturing plants, oil and gas plants. They can work in private sector that provide technical consultancy to both corporate and government companies.

So if you chosen this branch then yes, you have made a great choice, now give your best and do well.

Good Luck!!!!