I like it too! I also like the new sun - they now look like friends/companions.
Howie gives me the impression that he's younger than 5 - probably more like 2 or less age - it could be because of lack of hair with just the 1 strand. I like the style - but maybe a few more hairs on top would do better (5 year olds aren't bald) - Not sure it's important, and might wreck your look.
What I meant by color palette and age - Really young kids/babies - like the primary saturated colors, with high contrast. While their parents (aka people with the bucks) prefer more pastelly, softer schemes - as indicated by the abundance of soft pink, pale blue, green, yellow choices in baby clothes, blankets. Older kids and their parents can handle more sophisticated, wilder palettes, as well as the less saturated.
The color scheme/characters that you have are youngish - sorta reminds me of the teletubbie style. Kids seem to like characters/stories resembling themselves or older.
I wouldn't put too much creedence in what I'm saying - I have no pratical experience with selling to the parents of kids.
Go to the book store perhaps - browse and see the range of styles/stories for different age groups. There's also the
Society of Children's Book Writers and Illustrators - you may find more knowledgeable resources there
I repeat - I like what you've done!