The short answer is "Always test ALL patches and changes in DEV and TEST environments before applying them in PROD". SDL can't possibly guarantee that future updates from another vendor won't impact the stability of their product.
That said, I have not had any issues in the past. I always leave automatic updates to download in my DEV instances, and manually install them and smoke test all functionality once a month in Tridion before allowing them to propagate to higher environments.
Like John said - be careful of Java updates, especially in the CD environment. I have not had Java update issues in the CM environment since the Business Connector was dropped.