WORST EXPERIENCE I'VE EVER HAD IN MY LIFE.
4 rounds technical total. One round of interview, the interviewer's name started with 'D', literally the worst experience I've ever had(not exaggerating), he can't really explain the problem, a simple question and he described it like building a rocket, if the problem state is clear that would be also fine even though its building a rocket, however, the guy kept mumbling and you had no idea what he wanted you to do, left around 5 mins to solve the problem.
I gave iRobot a very high expectation, unfortunately the questions were all very easy and not challenging, and some of the interviewers can't even describe the problem clearly.
If you looking for a team with strong technical foundation and willing to exchange brilliant ideas, I suggest you look for other companies.