Nice cocktail. Was needing to use some leftover red wine and this worked perfectly. When mixed, it does a sweet flavour and tastes somewhat like a lower end Port wine. It was good.
Next time I would put some citrus juice and make it more in a sangria style.

A taste that will be quite familiar to Australians as it tastes like a still sparkling red wine. Very surprised how versatile this is. Might be quite dependent on the quality of your Shiraz.