Google camera is not available for all Android devices. They are only suppoted on Google Nexus and Android One series devices. Now to have it you have yo get it ported from those devices and pretty much every device has it’s version ported on XDA Forums. Now Google camera is the best camera application. It has many tweaks. You can blur background like in DSLR and you can take awesome HDR+ pictures. The HDR+ feature is far better from stock camera or other camera applications . The interface is the cleanest interface made by Google. I really love this application