I have nothing against it per se, but it seems that there is a trend in which "serious stuff" is graphically designed as if it were meant to be used by only children. There are many examples. One good example is carbonmade [1] which is a website to showcase professional portfolios (quite "serious stuff" if you ask me). I genuinely wonder where that trend is coming from. Is it because the current generation of engineers grew up watching cartoons? (Just guessing) Or is it because it is a simple way to make difficult stuff appear more friendly?
Anyway, I like the design, and I think the designers did a good job.
Basically, I think that Lisp and Scheme have a reputation for being unapproachable. This reputation partly comes from how we structure our communities, who we reach out to, and etc. But it also depends on how we message ourselves.
There's a very conscious decision in the new design to make things look playful and inviting, to encourage experimentation. I think that's super important. It seems like it's having some effect on encouraging people to become engaged, and it certainly doesn't seem to be doing any harm to those who are already into hacking parentheses. :)
I don't think it is simple to do successfully, but it is certainly a way to make difficult stuff more approachable. If you want to convey difficult stuff, you should make it approachable. Feynman, for example, was a master of using simple words to explain complex matters. We should try to do the same with graphic design.
(Carbonmade seems maybe to have aimed for "childish" rather than "simple", though, turning at least me a bit off)
I think it's cute - unlike carbonmade which really turns me off.
My only quibble is the cartoon next to "Guile is an extension language platform" - the main character is facing out off the edge of the page. I'd flip it to make the cartoon draw your eye toward the text.
(The same could be said for the cartoon at the top of the page, but I like that one the way it is.)
I had noticed this too, when docker.com seemed to slowly become more and more cartoony and juvenile, for lack of better words. I don't quite hate it either, it certainly makes the technology seem more approachable, but I think they may have taken it a bit _too_ far.
Stallman considers hacking to be "playful cleverness". To him and a lot of the old-time hackers, programming is fun and even "immature" or at least not super serious. Look at The Little Schemer, for example. Even Knuth allowed some jokes in his Concrete Mathematics textbook!
Anyway, I like the design, and I think the designers did a good job.
[1] https://carbonmade.com/