From what I understand you can configure SNMP Traps to be sent from the ESXi host to different targets and also configure the host to accept GET commands. So it's basically READ ONLY, at least I'm not aware of how to manage ESXi using SNMP. In case you didn't see this yet, take a look at William Lam's block post at Configuring SNMP v1/v2c/v3 Using ESXCLI 5.1
André