Piano by Color systems have been around for a long time, starting with kid's toys in the 1950s.
The general idea is to associate a piano key with a color, such as "Blue" equals "C" and so on. There are at least ten of these type of methods on the market today, and all are very similar, regardless of whether they are software based or book based.
The rationale is that children, especially the youngest, have difficulty with musical symbols, so why not substitute something else to get them started at the piano.
Ah, but there's a problem. Piano by Color, as used in these methods, uses a medium, color, that will have NO place whatsoever in the study of music or piano. It may get kids started, and bravo, but it lays no lasting foundation for music theory because there are no colors in conventional musical notation.
So, some of these methods try to counteract this irrelevance by adding the names of the notes to the colors. That's an excellent idea, for letters like A, B C and D will indeed have their place in the study of music, and thus using the letter names is relevant and useful not only at the piano but in music theory.
Such a method might be called Piano by Letter, and as such, it IS useful to children. There are various books out there that combine the letter names of the notes with notes on a conventional staff. While confusing, it works for some people, almost always adults. The problem is that when confronted with music not created for this special system, the student cannot read it.
But a method that relies on colors is really a gimmick to sell you on the ease of using it.
Far better to use a medium that has a place in the study of music, and will always be at the center of musical construction: numbers.
For years I taught using various systems like Piano by Color and Piano by Letter. But I found these methods confused students, who always forget which color was which key. Or Piano by Animal, a current product, if you want the height of irrelevance and foggy associations of symbols to keys.
In numbering the piano keys from 1 to 12, as in Piano by Number, we are in fact describing the classical "intervals" of music, a terminology at the very center of musical structure. Concepts like RED, BLUE and GREEN or CAT, HORSE and PIG may be delightful at first, but they do not have anything useful to do with musical education, other than easing a child's entrance into the world of the piano, which has a place, of course.
In general, I would conclude that all starter piano methods are a good thing, by Number, by Color, by Letter, by Animal, because they delay or soften the onerous task of reading music, the number one factor in quitting piano for most children.
But are all starter methods equal? I would choose one that has the most relevance to eventually learning standard musical theory and notation, and in that respect, Numbers easily beats the competition.
Get started easily, by all means, but do it the right way.