Very striking. You clearly have an eye for this stuff, and they're all great covers on their own. The only problem I see is that there isn't anything tying them together- especially seeing as how they are (as far as I understand it) episodes of the same novel.
Because it's episodic, they will probably be displayed together, and so you may need to look at them as a single unit. If you brought some consistency to the covers, (black back grounds, same font, same author placement and colour) they would compliment each other, building artistic momentum instead of competing. (This is also better from a marketing standpoint) But anyway, like I said, Great individual covers.