Its no secret that I am disappointed with google photos and particularly in the crippling of picasa’s wonderful sharing capabilities. However I am trying to be fair in the comparison and thus want to try and follow as much detail of the race between google photos and flickr apps on my phone as I can. So here is a comparison of (mobile) data use for last month including the period I was travelling (the light blue area of the usage graph on the right).
In theory the same photos have been uploaded to both services (in practise there are differences BUT more photos have been uploaded to flickr!). So the observation that google photos has used almost three time as much of my bandwidth for essentially the same task, is another stumble for google photos. The better news is both have used only a fraction of the space taken up by the actual photos, so they are obviously doing good things in terms of compression and effective image size/quality trade off.