It's like doing it internally, but without all the resources internal students get. I know some people doing the degree and I've seen how hard they work. I'll always recommend doing courses internally as opposed to doing via distance simply because internals get so very much more in terms of resources, but the choice is yours.
Would anyone know which universities are reknown for having a good external computer science course? I can't find any. I couldn't even find the one from UNE.