The wizard simplifies the process tremendously and generates the necessary spreadsheet and a fully functioning gadget within minutes.  However, the best part is the new features incorporated into the Checkout process.

Inventory - using the wizard, the gadget creates a simplified inventory control system whereby the inventory is reduced in the spreadsheet when the buyer processes the Checkout cart.  If the inventory is reduced to zero, the gadget presents an out of inventory on the website for that item automatically.  This works very well - thereby reducing backoffice maintenance to simply updating the spreadsheet when new inventory arrives in the stockroom.  A limitation to the system is that options need to be placed on separate lines instead of a single line with options - for example - a widget sold in red and blue needs to be setup as widget-red and widget-blue in order for inventory control to work properly.

Shipping - using the wizard, the gadget now allows "variable" dynamic shipping based on the buyer's location versus a fixed price.  This is an awesome extension of the Google Checkout process.  The seller sets up the basic terms of shipment methods and processing fees in their Google Checkout system.  The gadget takes over from there - when the buyer checks out the cart, the system will provide available shipping methods (as defined by the seller) and then prices out the buyer's selection automatically and adds to the buyer's shopping cart for final processing.

Oops - there is one downside to the new wizard - due to the integration back into the inventory spreadsheet, the gadget created will only work on a single web page with a single spreadsheet.  This means that the items for sale can only be displayed on one page and doesn't allow for multiple page segmentation (such as by brand or subject).  The Google development team is working on this and hopes to have a solution sometime after the new year.

Link to the new Checkout Wizard.