We eat this a lot, sometimes using beef or chicken, and find this an easy dish when we want a quick curry fix.
You can add a couple of peeled, diced pootatoes and about 2 cups of water for the final 30 minutes of cooking.
A family favourite. The Guiness mellows during the cooking to produce a yummy gravy. I do like Queen Dragon Mum's idea of adding the molasses if you don't like prunes as that takes the edge off the Guiness too.