Just upgraded a production environment to 3.5 update 1 and 2.5 update 1. Everything went surprisingly smooth. Looking at the Update Manager I noticed the total amount of 40 patches at this moment for 3.5. If you have a closer look you will notice that a lot of those are related to specific hardware or packages. I heard a couple of rumors that the Update Manager will do “selective” updates in the future depending on the hardware that the system holds. About the packages, I guess that will be history when ESXi is the only Hypervisor around….
Anyway, the upgrade went smoothly.