Twitter Heron is an alternative to Apache Storm with compatible API as it was developed from Apache Storm. The major difference I found was that Heron opts to get rid of Threads and going with Process based workers. This is surprising and I am not sure the any advantage it would have over Threads+Process.
Heron also has done away with DRPC which is the one thing I need to provide direct access to a Storm cluster. I haven’t seen an alternative being mentioned.
Most of everything else is same as Storm except the sales page for Heron is better of course :) The reason to explore Heron is ease of Production use and DevOps. It’s kind of difficult with Storm but Azure HDInsight might help as it has now Apache Storm 1.x supported in their HDInsight 3.5 version.
I hope to learn more from users of Storm and Heron who have been operating it in Production on what’s the pros and cons.