In mid 2017, VMware claimed the HTML5 based vSphere Client had 90% feature parity to the vSphere Web Client. Perhaps that is true, but what can be very frustrating is finding where some of the core operations have moved to in the “new” UI.
At this moment, I’m using vSphere Client version 18.104.22.16800. I had an unusually hard time pinpointing the method for adding a datastore to an existing host. It seems simple after you’ve found it, so here it is for anyone else that is having trouble locating the function:
Hosts and Clusters > Select the Host > Select Datastores > In the “ACTIONS” dropdown, select “Storage > New Datastore”