Spotifier here. One of the big risks that we identified with the Google partnership was exactly this: Google isn't exactly known for awesome customer service.
We've been very pleasantly surprised. The cloud team has been pretty awesome to work with, including lots of engineer<->engineer contact, walk-throughs of systems and code for critical dependencies, and solid support and collaboration. Exceeded our expectations.
We are much smaller, but also use the Google paid support.
I'd echo the sentiment here: my experience of the paid support for GCP has been universally excellent across Compute Engine, App Engine, BigQuery and Cloud Storage. This is across 30ish tickets, some of them quite complex.
I use the lowest level of paid support, I think it is the silver plan, and have observed similarly high quality levels of support. Sometimes you get a lower level support dude and have to convince him that your issue is real, but overall the support is good.
We've been very pleasantly surprised. The cloud team has been pretty awesome to work with, including lots of engineer<->engineer contact, walk-throughs of systems and code for critical dependencies, and solid support and collaboration. Exceeded our expectations.