Although it works and is solid, I wouldn’t say it’s fantastic. My impression is that Google makes limited investment in it to steer customers towards their own services such as Cloud Spanner.
- Major versions are 6 months late - Small instances are horribly slow - Integration with other services is poor (e.g. the Cloud Run integration doesn’t work with a database private IP, so you have to fallback to configuring a VPC and connecting the standard way) - IAM authentication, although great when it works, is complicated and poorly documented - The UI has very few features, for example it isn’t possible to query the database from it - Although I’ve never seen any provider have it, automatic upgrades between major versions would have been nice.