Would have been better if...

Is it a supernatural twist though?

Doesn't it just make you consider that there might be a supernatural element? Myers could, in reality, have simply crawled a few yards and is dying in the rose bushes or in a hedgerow.

The ending kind of means that Michael haunts everywhere and everyone in Haddonfield (if he didn't already). He doesn't necessarily need to be supernatural to do that.

We're still nowhere nearer to comprehending what Michael is and Loomis's idea that he isn't human is as good as anyone by this point.

Supernatural or not (and not taking the sequels into account), I find the ending to be one of the most effective in film history. The mysterious Shape still lurks around and it’s a creepy thought.

I've always had mixed feelings about it as well. I know Loomis goes on about him being evil and he shows superhuman strength, but the ending took it to another level. Maybe he should've been shot only once. I do agree with others that it's a creepy ending.