Boeing requires a very formal panel interview. During my first round interview, data flowed only oneway, so there was little opportunity for a natural conversation about about the job. Five questions were asked by the panel. My interview panel consisted of the hiring manager, a group peer, an internal customer, and a HR representative. Standard subject matter expertise and behavioral questions were asked, so be prepared to respond with a STAR example from your work history (describe the situation, the task you accepted, your actions, and the results & outcomes.) At the end of the conversation, I was given a few minutes to ask questions. However, as I understand the Boeing process, you are judged and "scored" on your panel questions and not given much benefit for demonstrating excellent insight & expertise during the five minutes of Q&A. Therefore, it would be wise to anticipate the panel's questions based on the job description (which in my case didn't even provide the right clues about what would be important to the panel questions.)
This formal interview is a screening step. After getting through this step, I was called back for another interview. My second round included better natural conversations, although I was asked a few more standard interview questions. My second round was much more about my style and fit to the opportunity.
It doesn't seem like the first round interviews are very valuable to the hiring process, so from my perspective it was a negative experience. Even the managers conducting the interview don't like the format -- but apparently it's a mandatory H.R. step at Boeing "in service of greater objectivity." By comparison, the second round interview was much more enjoyable.
There was a long delay between when I originally applied for the role and was scheduled for an interview. Second round interviews came much quicker.