What is the use of doing an M Tech in JNTUK?

M.Tech has generally pursued research purposes. If you are highly interested in your subject then go for it without any further hesitation. To enhance your knowledge is never a decision that would make you regret it later. 

You might even be offered an opportunity to opt for the post of Assistant Professor or Research Assistant. Your B.Tech qualification would suffice the criterion for private companies as a degree in M.Tech is not much of value in the corporate field. 

You may opt for this course if you are immensely interested in acquiring a job post as a research assistant, etc. Otherwise, it would merely be a waste of time.