My interview had 6 rounds. They provided a take-home assignment which took 2 days and 6 cups of coffee to complete. In total, I spent some quality 20+ hours on the entire interview process.
Quick intro about me: I have been in the field for many years and I have worked at different companies in various different capacities.
I have reasons to believe that this company is very unreliable including:
1. They give their work to you as an exam for your interview. Basically, putting you under pressure since you are applying for a job to do their work on the table for free. This is unethical and unacceptable.
2. On one hand, their recruiters highly encourage you to fearlessly share super technical answers or details with them in the interviews, and on the other hand they go ahead and ask you the questions that they cannot solve at their current job or for the current project (or projects they have failed at so far and over the years). This is an abusive, selfish and potentially illegitimate behavior which is still unbelievable to me.
3. They gave no feedback after hours of interview.
4. I got really negative vibes from their HR. They had nothing to say basically and very unprofessionally so. I sensed strange patterns in their behavior and conduct. Pretending that they were looking for talent or positive character, traits, etc. in you,they were just looking to see if you are good candidate for their exploitation purposes. Namely, a truly knowledgeable engineer or scientist who can be easily abused (say because their EQ is not sharp enough) without them noticing or complaining.
5. They pretended that there is openness in what they do and they publish their work and all. But I strongly sensed in many occasions when I talked to the interviewers that there is a lot of destructive competition and politics going on there and that there was something to hide. This does not jibe with the spirit that they are trying to associate themselves to.
6. I was supposed to talk to an interviewer, which at the last minutes changed to another. One of the interviewers expressed their high degree of surprise because that was the usual way for doing things and that they found something strange happened. I was then interviewed by someone else which was indeed weird and unnecessary.
7. Given that the interviews went much better than an average interview (trust me they did), I got rejected way too fast and right after the last interview. Given the entire set of observations, I strongly believe that they had decided to reject me in advance. Hence, doing the last interview was not justifiable or ethical in any way which makes matters only worse. That was nothing but pure abuse and unjust attitude.