Beta reader for a cryptogram puzzle book

I'm publishing a cryptogram puzzle book and I need one sharp beta reader to go through it before it's final. I want honest, critical feedback. What's confusing, what's boring, what doesn't work. Please don't just tell me it's good. It's for adults, about 140 pages, with short stories and puzzles you solve by hand, plus hints and full solutions. I'll keep the details light for now. You'll get a PDF excerpt: a few complete puzzles from easy to hard, the how to pages, and the matching hints and solutions. Enough to read it and play it like a real buyer would. What I want from you: 1. Stories: interesting and believable? Do they feel distinct or blur together? 2. Writing and style: is the voice good and consistent? Does it read premium or cheap? 3. Puzzles: solve a few. Fair and solvable from the clues, with no guessing? 4. Difficulty: does it build well? Too easy or too frustrating anywhere? 5. Hints and solutions: helpful without spoiling? Clear and satisfying? 6. Anything confusing, plus any typos you catch.
Bottom line: would you buy this or gift it? What would stop you? Quick notes per puzzle plus a short summary at the end is perfect. This is about the experience, not a full proofread. Who I want: a native English speaker who genuinely likes puzzles or mysteries. You don't need to be a cipher expert, a smart regular solver is ideal. Reliable, detailed, and comfortable being blunt. Logistics: this is an early copy, so please keep it confidential and don't share it (happy to sign a short NDA). It's a focused review, roughly 3 to 5 hours, fixed price $120 to $150.