One of the most intensive interviews I've been on for this type of position. Most companies I've had experience with will do a phone interview and then an in-person interview, here there's the phone, written, in person, and second in person with tests along the way. Not saying this is a bad thing though, they just know what they're looking for and want to make sure they're not wasting their time. I see a lot of people have said the interview process is extremely difficult. Although there are many stages, the actual interviews are not too difficult at all. It felt more like a conversation to me, and they ask you pretty expected questions, nothing to trick you. As mentioned in other posts, some of the questions are repetitive but they're all from different people so they're just trying to get to know you and your skills as well.
Although the there were a lot of steps, the process was quick and I heard back within a day of each interview, except the final it took a little less than a week which is expected. Everyone was extremely helpful and kind along the way.