Looks interesting, especially the "lessons learned"-section.

However, the latest version (as of writing this) is Elasticsearch 0.90.7, released November 13, not 0.90.5 as stated in the article, which I guess relates to lessons learned, part 3: "TRY to keep up with releases".

There is a lot of stuff happening right now with Elasticsearch as they're nearing a release of 1.0 (which I'm told we're to expect in H1 2014), and a lot of fixes/features are still showing up in new 0.90.x point releases :)