This is very likely the LOUDEST book I've ever read! I don't think I've seen so many contrasting colours together in a single place before!
Luckily, this makes it easy to tell the characters apart! (unless possibly if you're colourblind, but I expect that's still easier than if they're all a solid colour, since they still have patterns)
I also tagged this as "lgbtq" because I'm FAIRLY certain Bo's gender is specifically unmentioned for a reason, which is easy to do when the story is told in first person (hence diary!). Even the book description avoids saying, "Bo is a (gender here)!" I actually like this, because there really isn't a reason for any of them to have gender at ALL, since the book *starts out* by explaining that unicorns reproduce asexually (not using that word, but they do) by just *popping* into existence on particularly starry days.
Fun times!
About the one concern I have is that Bo states that "We [unicorns] glow when we're nervous." It's not that kind of series, but I'd imagine the glowing would make them flag-waving targets if some predator came along to eat them. Just kind of unfortunate, even though I'm sure it was supposed to be a cute quirk.
Recommended for young unicorn fans of ANY gender! :D