Fair assessment, except that the site is bad. Methinx I ran into an invalid puzzle, for one. If you want sudoku "for kids", http://www.sudoku.com.au does two each 4x4 and 6x6 puzzles every day.
The second puzzle I tried was invalid, but I like the idea of Sudoku for kids. My grandaughter is 6 and numbers orientated, she takes an interest, but gets lost with the larger sizes.