Too time consuming, rather wasting. They have an aptitude test the a couple of technical interviews and a final HR interview. They could wrap it up in matter of hours but take about 1 to 2 days to finish.
The aptitude test is useless and in fact not accounted at all. They conduct it as a formality, no matter what your score is, you will be passed on to the interview round. This is sheer waste of every bodys time.
The interviews have basic technical questions which would be easy to answer. They also involve some logical/analytic questions which are basically puzzles that one solves for CAT and such other exams.
Appearing for the HR interview indicates that you been selected for the job(90%). You get to negotiate your salary here.