Rob J Hyndman has a very nice review on Google scholar metrics [1]. Here is his ending quote:

  In sum­mary, the h5-index is sim­ple to under­stand, hard to 
  manip­u­late, and pro­vides a rea­son­able if crude mea­sure of
  the respect accorded to a jour­nal by schol­ars within its
  field. 

  While jour­nal met­rics are no guar­an­tee of the qual­ity of a
  jour­nal, if they are going to be used we should use the
  best avail­able, and Google’s h5-index is a big improve­ment
  on the ISI impact factor.

[1] http://robjhyndman.com/researchtips/google-scholar-metrics/