Interview is good. But process of calling on weekends and prolong to late hours is not good. There should me sufficient interviewers based on interviewees. Nothing more than this , there is no use of asking to write 30 words.

Rounds are pretty good. 1. Question on what technology you are working. 2. Mainly they will ask on problem solving. 3. Design level discussions. 4. Based on the position you apply, additional rounds might be there. 4. HR discussions