As Google discontinues Maps Views this week, without having a replacement ready (though they promise all functionality will return through Google Photo and Google Maps), I like to point out a new kid in town, called Round Me.
Round Me has a great web app to manage your photo spheres (which works beter than what Google had in Views, IMO), as well as mobile apps to show off your spheres. The iOS app even has great support for Google Cardboard (which the Google iOS apps didn’t have), the cheap VR viewer for use with smartphones.
I’m still exploring all features as I start uploading my existing spheres onto it, but it shows great promise.
Of course, the main disadvantage is the fact that they don’t have as big an audience as on Google Maps.