I applied and they responded very quickly asking my to complete a skills exam. It was fairly challenging, at took a bit of time, but I completed that and returned it to them. Within a day or two their HR coordinator set up a phone call for me. I'm not sure who the person's title was that I interviewed with, but he asked me to explain a variety of concepts, mostly related to iOS. It was fairly straightforward, he was pretty laidback, and answered several of my questions about Mutual Mobile. Later that day, I received another call unexpectedly from their Director of HR who asked me some questions about compensation and answered some of the other more "culture"-type questions I had. About a week later, he called back and made a verbal offer to me. (I had unfortunately already accepted another offer.)
Overall, they didn't communicate what was going all (during that week, I was unsure of my status), but every other interaction I had with them was fast, which was nice. The company seems to be a good place to work, everyone I spoke with really enjoys their work. If I hadn't taken the other offer, I probably would have accepted their offer.