It was good. Very Kind. There were 4 more phone interviews. And the final interview seems like presenting my research works in person. But, i didn't go on to the step.

There are parts of the interviewing process that test your skills, but others are honestly quite flawed. Interviewers frequently ask you to dive deep into a problem without clearly specifying what is it that they would like to know about it. Many of them are actually ill prepared with good questions and try to make something up during the course of the interview, just for the sake of asking a question. Not sure how all this allows them to fully evaluate the capabilities of a prospective candidate. Overall, while they claim to be hiring the best, their interview process, especially on-site is sub-par, and you may exit even if you answered most of the questions right.