The first interview is just with an HR rep who speaks to you about very basic things. Very simple with no preparation needed.
The following interview was with two managers who asked about past projects and interests within programming. Not too hard, but I wasn't on my game. The people were very nice and probed deeper into every project I spoke about. They were very knowledgeable.
The only thing that frustrated me was that they told me there would be another interview, and then never reached out again. I understand they didn't want to hire me, but they just led me on a little bit.
Overall, a good experience, except for not getting the position.