The new SPA version is far, far slower than the old HTML version, and uses a truly insane amount of memory. I have 2 gmail tabs open, and according to Firefox's about:performance page, one is using 140mb of RAM, the other is using 95mb, and both are at the very top of the list in terms of CPU usage. Above even YouTube in both CPU and memory, which is itself fairly bloated.
Google Cloud Console felt slow to me too. And the user experience could sometimes be better too. For example: I set filters in a table of items, clicked many times to Next to paginate on the 10th page. Then I accidentally clicked on an item on the page, detail page shows. Clicking browser' Back button takes me back but the filter is cleared and I am on the page #1 again. State was not persisted so I could start filtering and paginating again. I am not 100% sure but I think it was the Quota listing. The old, document-style pages used to hold state!
From an architecture standpoint, it does also allow a much simpler separation of concerns.
That said, it does it get used more often that it should and can take more time to build than a multi-page app.