Pretty simple app, but well executed. One irksome point is that the app does not support 360 spherical photos at all, even though their website does. I sure hope they integrate viewing spherical images in the app sometime soon, including single lens and double lens VR viewing.
In its current form, you have to find a photo in the app, copy a URL, and then paste that URL in to Safari to view a mediocre spherical view, panning around with your finger only. Not sure why the app is worth having if the website is more capable.
R.C.K.1.2.3 about Flickr, v4.2.0