As someone who's tested countless activity books with my nieces and nephews, this unicorn-themed I Spy book is a standout. The illustrations are vibrant and whimsical, instantly capturing kids' attention with rainbow colors and glittery details.

What I love most is how it balances simplicity for younger kids (ages 3-4) with enough challenge for older siblings (up to 6+). During testing, my 4-year-old niece squealed with delight finding the hidden cupcakes, while her 6-year-old brother enjoyed racing against the clock.

The sturdy hardcover binding surprised me - it's survived multiple toddler tantrums and still looks new. Each page tells a mini-story, making it perfect for bedtime when you want something more interactive than traditional storybooks.

My only critique? The glitter accents shed slightly over time. But watching kids' eyes light up when they shout 'I found the rainbow crown!' makes this minor flaw totally worth it. At this price point, it's become my go-to birthday gift for unicorn-loving kids.