Mr. O'neil..
I've been a huge fan of this series, I can't lie, you have many talents not many people have, not just on Newgrounds, but anywhere else on the internet as far as I'm concerned, and I'm sure others will agree with me.
I was worried that, like many other Author's on Newgrounds, that you would have gotten lazy after the third 'series' and would stop making them, so I'm definitely glad to see the 4th Flash up, whether it is better or worse than your past submissions is irrelevant, I'm just glad you've taken this project seriously.
Now that's out of the way, my review.
I have noticed through each one of your submissions, the art work gets noticeably better and I would like to see that progress. As for the humor, I feel as if your third submission you might have lost your touch and swayed off to the wrong direction, which I personally think you began to do, but needless to say you're back on the right track. You definitely haven't reached your potential though; the trademark of these submissions is the mixture between Satan's alternate personalities, completely innocent, to completely demonic. The sudden demonic changes are absolutely brilliant and you do them very well a lot of the times. Others it does seem as if you 'force it', so put it in when you find the closest opportunity. I feel as if I've noticed it; I know for a fact you're aware that is where a lot of the humor lies in the flashes, and it is something that will not die for a very long time, because it's original. On the condition that you don't over do it, of course.
The reason I gave you such a low rating is because the plot to this flash seemed blind to me, you didn't seem to know what to do with it, or with the ending. You could've hit gold and made a brilliant ending but, it could be because you wanted to finish it quickly, I don't know, but it seemed pointless and unoriginal. Unoriginal is NOT a word I would use to describe somebody with your talents. If I was rating this in comparison to other Authors; 10/10, but compared to the usual structure of this series, I felt as if you lost the plot half way through.
I need to point out that the sudden inappropriate things Satan does, like lubricating his hand the way he did, and his 'cheeky' face expressions, his stupidly, yet innocent body language (like the poncy run he did in the second episode) was a gold mine when it comes to humor, as far as I'm concerned at least. You need to keep those little tints in Satan's personality that completely contradicts his stereotypical behaviour in your future submissions, because that is where the heart of the humor is. Of course there are other things in your submissions that make the audience laugh but nobody can argue where the heart of it all is.
Thank you very much for making this series, I genuinely hope you continue and get recognised because you have potential. Keep these submissions up. 5/5