[jdoliner]

This is a very good question. There's a growing sentiment in the Hadoop ecosystem that MapReduce is in someway passe and I think it's somewhat unfair. A lot of the confusion comes from the fact that people don't distinguish between Hadoop's implementation of MapReduce and MapReduce the paradigm. As a paradigm MapReduce is actually very general. A good example of this is stream processing. Hadoop has completely separate implementations for stream processing in Storm. However there's no inherent reason MapReduce can't operate on streams. In fact, in pfs where the file system can be thought of as a stream of commits that's the only thing that it does operate on.

So tl;dr we think that a better implementation of MapReduce can be a much more general tool than Hadoop's MapReduce is.