That was the same problem I had with that custom life size bust seen a few months ago. The facial expression wasn't a familiar one. Everything else looked great though, but if we don't have an image of Heath in a similar expression, it is really hard to tell on the likeness. But I'm sure its there. If not, it is close enough. It looks like the Joker and that is enough for me.
Ya, for me, likeness to Heath is really down to a curiousity factor, even if it's off, this is one badass looking figure and going to be worth every penny.