Okay, I'll throw in my thoughts here for a moment:
Firstly, in regards to episodic themes, I'll admit it - they've been done before. In many isntances, they've been done better. That's fine by me - when I started the project I was kind of instilled with a sense of tradition and deliberately chose to go with ye ol' standard. The only thing that changed was that I originally intended for some icy-hell maps along the way but never really got the theme to click the way I wanted it too.
As to the discussion re: theme variation. I'll say this: I tried very hard to take each theme and make a few unique looks. Not saying that they're different from all maps ever, but rather that the individual maps in the wad itself are distinguishable. Now, this didn't quite work out the way I wanted, especially in the second episode's Brick-o-mania, but I eventually got the concept to work in Ep 3. Many of the maps have an identifiable concept behind them - ash, marble, gstone, gothic, wooden, redrock, and the eventual concluding map. Joshy and skillsaw also went with unique looks making the only episode where each map is completely distinguishable from the other. It also features some of the best maps design-wise.
Now, gameplay variation - I have two responses. Firstly, it's a one-man megawad that was intended to have consistent gameplay ideals. Secondly, I did try and mix it up on occasionally. There's linear maps, there's sandbox maps, and there's nonlinear, non-sandbox maps. I do repeat a number of traps throughout the wad, and I very clearly believe in certain concepts (mixture of monsters, when and when not to use them, etc.).
If you didn't enjoy the wad, that's cool. Not everyone will. I do appreciate the fact that it's being used in the same sentences as Scythe and Vanguard as they're two of my favorite wads (I'd top-5 them both).
Now that being said, let us please get back to bug-reports and that sort of goodness.
EDIT: Also thank you everyone for playing and commenting. You guys are the coolest.