NTTF is a good option even if you are an average student. Let me tell you the experience of my friend who recently graduated from here.
He scored 45% in 12th with a science background. He was able to score 600 in the state-level exam. He chose Mechatronics and did well in academics. Currently, he is working with TATA Steel with 40,000 per month. The salary is a bit low but it is not bad when you are a fresher.
NTTF will be a good option if you are looking forward to pursuing a diploma. However, you must know that the institute is not recognized by AICTE currently. Thus, it will limit your opportunities to apply for any government jobs in the future.