Definitely worth checking this out: FAQ: Human Microbiome, January 2014. It is a report from the American Academy of Microbiology and it is really well done. In addition to the report itself there is also and Infographic and a nice little handout.
The report was based on discussions with a collection of Human Microbiome Gurus:
And it was written by Ann Reid and Shannon Greene. It has a variety of useful tidbits and has a reasonable number of caveats – such as “it should be noted, however, that at this point, most studies, even in mice, are looking at correlations between gut microbiome composition and factors like weight, insulin sensitivity, and other metabolic measures.”