I've made my way through 3 and a half of the original Kageyama episodes, and they're... bad. It's hard to succinctly describe just how bad they really are.
Episode 1, which is about the battle against the MP Evas and you'd THINK would have a really easy time being a great read, wastes a significant amount of time blathering about bullshit like predictive computer modeling. Kageyama, sadly, cannot make any of his technology porn asides feel even a little relevant or interesting. (Contrast with, say, Michael Crichton, who could babble on for pages about some topic you know nothing about, and make it not only interesting but suspenseful.) A sense of time and place is poorly established. Pacing is stilted. There's SOME interesting and cool stuff in the prose, but the ideas aren't really developed at all.
Episode 2 fares quite a bit better. I actually liked this one; I got through it easily. This is the one about Eva-Quatre crashing from orbit for ~REASONS UNKNOWN~. It spends a some time at the start with a classroom scene where Rei is telecommunicating with her clones in orbit -- yes, she's doing this at school for some reason -- and broadcasting through a robot cat named Nyankichi (I can't make this shit up). Meanwhile, Asuka is staring at her and contemplating Rei's beauty and humanity. It's weirdly shippy. Then Rei starts seizing or something, and Asuka has to give medical treatment according to Nyankichi's instructions. Rest of the episode is about Eva-01 trying to intercept the falling Eva-Quatre and trying to stop its S2 engine from going haywire, like some weird fusion of Sahaquiel and Jet Alone.
Episode 3 is bad. It is so bad. It reads like a rough draft or something. Starts off... FINE, with plans for Eva-01's renovation into "Super Eva" (lol what a shitty name) getting discussed. Then the first Angel Carrier shows up and it turns to total shit. This is supposed to be a really important battle that sets up Anima's whole "Shinji is Eva-01 now!" thing, but somehow Kageyama makes Eva-01 getting double-teamed by a zombie MP Eva and a possessed partly-disassembled prototype vague and tedious. How quickly it ends once Eva-02 gets there really rubs it in how few shits Kageyama gives. The final scenes taking place at Nerv HQ are weirdly truncated, breezing past some awfully strange developments like they're nothing at all.
Episode 4, I'm still working on, but get this: it breaks continuity with #3 so badly that not only is the end of the previous episode retconned, important events anticipated at the end of #3 are COMPLETELY SKIPPED OVER. Starting the episode, you're left with effectively no idea of what is actually going on anymore. Something rather alarming seems to be happening, but nobody is treating it as something alarming, instead rambling on for countless paragraphs with technojargon that takes forever to get to the point. It makes one YEARN for the bridge crew's overdramatic reactions in the anime. Eventually we get to a sequence introducing Rei Quatre, which is ... better than what came before.
Even though Seven Seas isn't publishing the Kageyama episodes, I'd feel uncomfortable posting them somewhere in Google's reach for the moment. I'm not sure how many more I'll do. From what I've seen of Yamashita's rewrite, it's better in almost every way. He seems to totally skip past the MP Eva battle, which is a shame IMO, as he could have written a better version easily. I get the vague sense that he's transposed the best moments from Kageyama Episode 1 into the Angel Carrier battles, though, so maybe nothing has really been lost.
I also ended up translating most of the Final Episode/Chapter/Whatever, because BlueBasilisk got me curious about what the deal with that new Eva-01 was and I didn't want to wait over a year to find out. I'm clearly insane.