This is great news for the Gui users out there - I had seen this from the Partner portal and hadn't noticed it in the actual admin.microsoft.com site.
If you click through to the exchange admin center you get prompted to use the new Exchange admin center and selecting that will dump you back to the original partner's exchange portal which is a shame.
The classic Exchange portal seems to work using the switcher AND you can now convert a regular mailbox into a shared mailbox and back again which was not possible in the old Partner portal delegation model.
Is there going to be a change for delegated access with powershell? We currently need individual named accounts in each tenant so we can run powershell scripts (which is the best way to keep an MSP efficient and having reproducible steps)
Also it doesn't appear to have the same functionality for Azure subscriptions - is that meant to be covered by switching subscriptions?