vCenter Server now supports the following external databases: Oracle 12c, Microsoft SQL Server 2012 Service Pack 1and Microsoft SQL Server 2014
The vCloud Hybrid Service (vCHS) introduces a new container, Hybrid Cloud Service, on the vSphere Web Client home page. The Hybrid Cloud Service container contains the vCHS installer and the new vCloud Connector installer.
The vSphere customer experience improvement program is introduced to collect configuration data for vSphere and transmit weekly to VMware for analysis in understanding the usage and improving the product.
Below are the new vSphere 5.5 update product support notice,
Starting with vSphere 5.5 Update 2, Windows XP and Windows Vista are not supported as vSphere Client Operating System.
vSphere Web Client is not supported on the Linux OS as Linux OS are no longer supported by Adobe Flash
There is no more support for IBM DB2 for vCenter server databases.
vSphere Data Protection 5.1 is not compatible with vSphere 5.5 so if you want to use vSphere Data protection with vSphere 5.5 update 2 you have to upgrade vSphere Data protection to newer version.