This release primarily fixes a bug which affected some users when they updated their shop to VirtueMart 3.4.0. Third party developers should update their systemplugins loading the VirtueMartConfig class analogue to the virtuemart system plug-in. For details please use this link to the forum thread
Also VirtueMart 3.4.2 gives users the oppportunity to test PayPal Smart Buttons. PayPal Smart Buttons offer several style options to customize the look and feel of your smart payment button. You can also use options to display multiple funding sources to the buyer, when appropriate. It is very easy to configure and deprecates the simple "PayPal Exress" and "PayPal Credit" options.