This bar is really an acquired taste. Even I'm not sure if I love it or not. Sponge toffee is a strange thing, it tastes kind of burnt but kind of sweet at the same time. The chocolate helps kill the burnt taste, but the toffee is still the major flavour. Sponge toffee is also really sticky. You wouldn't think so at first glance, but once it's in your mouth it melts like crazy. It also sticks to your teeth a bit, although I seem to remember it sticking more when I was a kid.
There are two ways to really eat this bar. If you don't mind the sticky you can let it melt in your mouth and coat your teeth in sticky goodness. If you don't, I recommend you crunch in. Having said that even when you crunch this bar, I find I get pieces stuck to my teeth. To good thing is that if you’re patient the sticky stuff will eventually break down and your teeth will be sponge toffee free. But I understand that some people just hate that feeling of sweet stuff stuck to their teeth.
I think you'll either hate this bar or love it, that really all depends on your feelings about sponge toffee. It's not really an average snack, and it may be something that will never grow on you. Having said that, I like it and I'd eat it again.