The shield works fine, easy as pie to attach wires and string everything together.
But ... I missed this note: "The terminal blocks will make it not possible to plug a USB Cable into a Side Mount USB TinyShield. Plan to use the Top Side Mount USB TinyShield instead."
The solder joints underneath this board extend out such that you can't plug in a USB cable into the programming board undermeath it. This means you can't have this shield and the programming board on at the same time. Perhaps another solution is for this shield to be redesigned by rotating the connectors 90 degrees such that the solder joints aren't over a normal USB programming shield?
In any case, to solve this problem, search for "Top Side Mount USB TinyShield". This is a normal "USB TinyShield" but set the "USB Connector" option to "Top" $14.95.