I do have the first volume of the manga and I thought I'd give it another go after finishing Crybaby. What's so interesting about manga Ryo is that he's not nearly an emotionless drone as he is in Crybaby. He seems as though he genuinely cares about Akira's safety and hates the idea of turning him into a demon to the point he's actually shedding tears, where in Crybaby I got the sense he's manipulating Akira. Both him and Akira seem like genuine friends in the manga, something I rarely got in Crybaby. If anything, you have to wonder why Akira would be friends with a violent psycho like Ryo.
That was one of the major things I couldn't stand in Crybaby because of how it ruined that strong relationship between Ryo and Akira, in my mind it also ruined the impact of
Ryo's betrayal and the final moments of mourning after he killed Akira. Crybaby never made me understand how the two of them were even friends past them having to be for the sake of the story, past them making Crybaby Akira pre-demon semi (if not fully) retarded.
While them changing up Ryo was the most glaring issue for me, what they did to Akira made me feel like they also didn't really get his character either. In the manga he's a good person that's just more on the cowardly side, but when Ryo needs him he's right there by his friends side even if he might die. Then Crybaby Devilman Akira is just a massive step down across the board and felt entirely disconnect from pre-demon Akira. Manga Devilman Akira was different sure, but no where near to the same amount and you could still see that he was still the same good person at heart.
I kinda have a harder time sitting through the manga though because the beginning suffers from an insane amount of exposition dump. I do get a clearer picture of what the demons are and what they're capable of (I don't even think Crybaby explained that until the final episode), but it could have been paced better in my opinion. Once the story actually gets going it's far more enjoyable, plus I think my impatience stems from having just finished Crybaby and wanting them to get on with it. Also for some reason the American release slapped on Shin Devilman, that midquel series where Akira goes back in time and influences history, without even a hint that it's not the original manga. When I first read it I had no idea that it wasn't the original story so it felt so out-of-left-field and stupid that Akira's going back in time and killing more demons. Plus it completely slows down the story for shit that accomplishes nothing to the overall narrative. That's not the fault of the manga necessarily, but if you're just trying to get into the story the American release makes it a little harder to swallow.
I originally read Devilman through scanlations a while back, also remember the beginning to be a bit of a slog. Initially I was excited for the western release since I could finally own the series, but after hearing about Shin Devilman just being slapped in I've kind of held off. Might just bite the bullet and get the series anyway and just skip over Shin Devilman.
None of this to say I don't like the manga because honestly I really like Go Nagai's art (something about old manga style appeals to me for some reason) and the story's not nearly as stripped down so I get a much clearer picture. The violence also feels a lot more impactful due to the way Nagai draws the fight scenes; fights have a lot more weight to them where in Crybaby it feels a lot more like characters are made of paper and fell apart easily. It's just as a newcomer the pacing can get a little slow after the brisk pace Crybaby had.
I've always been a big fan of Go Nagai's manga even if people shrug them off as wonky gory perv fests, there's just something really nice about how he draws action. It's also interesting to see how he evolves story ideas, like his short lived Maou Dante being the base for the later Devilman.
If you want something short but really fun that he wrote I'd recommend Guerrilla High.
I put Crybaby in the same league as the Berserk movie trilogy. It's a fine entry point for those wanting to give the series a shot, but once you're done with it you'll want to check out the source material to get a much fuller story, while veterans aren't going to get nearly as much out of it. Though from what you're suggesting Crybaby makes far more radical changes than the Berserk movies.
I think the underlying major problem I have with Crybaby is the kind of fans it attracted, not helped by it being a Yuasa anime. A lot of them have no interest in reading the manga or even watching the previous OVA, I've even seen some claim it's 100% better than the source material somehow. I wouldn't mind as much if Crybaby did get people interested into actually exploring Devilman, but for many the series has become the face of Devilman.
