AVOID THE BOARD BOOK EDITION of this book. Get the original picturebook.
This book sets a high bar. It is character-driven, instead of flash-card style. Two seussy animal guys march around exploring the alphabet together while representatives of each letter parade across the stage of each surreal page. Geisel handled tricks in phonics well: e.g., instead of the standard 'x-ray' and 'xylophone' just to keep the 'begins with' structure, Seuss switched to "x is very useful when..." and let us see 'x' where it actually shows up in the most words. He also presents letters in digraphs and blends; and lets vowels make multiple sounds (like they do).