Gibson, Dunn & Crutcher has published useful (if somewhat defense-centric) summary of decisions under the 2015 FRCP Amendments.  According to the executive summary:

In contrast with the turmoil in e-discovery several years ago, e-discovery in 2016 was generally on a stable and very positive trajectory.

Highlight of the Year: Courts’ Application of the Rule Amendments.

In our view, the major e-discovery highlight in 2016 was how courts applied the e-discovery amendments to the Federal Rules of Civil Procedure and, for the most part, did so in a fashion that was very consistent with the drafters’ intentions. Decisions applying the amended rules addressed many of the prior, oft-cited flaws in the e-discovery process, such as unpredictable and unfair sanctions rulings and runaway discovery.