GP 2013 includes a number of useful enhancements. These are the seven I really like:
Home Page and Area Page Elements – You can easily change the way your home page and area pages look.
Purchase Order Tolerance Handling – You can specify high and low tolerances for receiving.
Purchase Order Prepayments – (Been waiting for this for a decade) You can create check payments in payables, that can then be applied to purchase orders.
Sales Orders – Related Items – This helps your customer service people entering orders, suggest other items your customers might be interested in.
Multi-select Serial Numbers – Makes it easy to select multiple serial numbers.
Tracking Serial/Lot Numbers on Drop Ship Orders – Allows you to more easily track serial and lot numbers on drop shipments.
Consolidated Sales Orders – If you use Advanced Distribution, you can combine information from multiple orders, onto one invoice.
Here's a video that shows this new functionality: