It's also by Martin Odersky, but also with Erik Meijer and Roland Kuhn.
Reactive is split into three "subclasses". The beginning part, taught again by Odersky, was a pretty useful extension of what was taught in the first class. As with the first class, the lectures were very well thought out. Although, some of the examples abandon the beauty of side-effect free programming, which was a letdown after really being turned on to that style in the first course.
I did, however, find the final three lectures on Akka to be very well taught. I had no experience on actor model programming, but I came away very intrigued by the possibilities.
A complaint that spans all three sections was that the assignments could be better focused on the the concepts at hand. Each can require a fair bit of constructing your own test and debugging frameworks to figure out how to pass the rather opaque and unhelpful automatic grading system. I eventually lost patience and quit doing the assignments after floundering with the tools.
Erik Meijer's lectures -- at least in the first iteration of the course; maybe they've gotten better -- were riddled with errors, confusing exercises, and an overall lack of coherence with the rest of the course. It pains me to say this because Erik seems like a cheerful guy and I really wanted to like his lectures, but they are a mess.
Even Roland Kuhn's lectures, which are pretty good and a lot clearer than Erik's, didn't manage to sell reactive programming to me. One glaring problem was that the actor model seems to throw away most of Scala's static type checking, which we had learned on the previous functional course. Suddenly it's ok to pass whatever message to actors in a way that seems closer to dynamic typing.
See http://noelwelsh.com/programming/2013/03/04/why-i-dont-like-... and http://www.chrisstucchio.com/blog/2013/actors_vs_futures.htm...