You can review the complete list of new features and bug fixes here.
http://www.syncfusion.com/squiffler/versioninfo/1.5.1.1/readme.htm
Instructions for downloading
If you have version 1.5.0.0 installed (you can get version information from the
Essential Suite readme file, readme.htm installed in your Essential Suite
installation folder) you can download the service pack from here:
http://www.syncfusion.net/squiffler/patches/v1511/es_1.5.0.0_to_1.5.1.1_sp.exe
Customers who participated in the Service Pack Pre-release testing, should get
the service pack from here:
http://www.syncfusion.net/squiffler/patches/v1511/es_1.5.1.0_to_1.5.1.1_sp.exe
The full install of Essential Suite 1.5.1.1 is available here:
http://www.syncfusion.com/squiffler/SyncfusionEssentialSuiteSetup.exe
Note: The service pack does not contain the updated documentation, whereas it is
part of the full install. The service pack does update all the binaries and
source code.
Instructions for installing and unlocking
You will not require any unlock keys for installing the service pack. Product
unlock keys that were sent to you when you purchased the product will work if
you choose to install the full version.