Looking for Sudoku puzzles testers

I am currently looking for testers of my Sudoku puzzles. As part of my new book, I am showing readers how to generate Sudoku puzzles of varying levels of difficulties, using a computer. I wanted to get readers feedback on how difficult my puzzles are, and whether they really fit in to the level of difficulty they are categorized in.

Beta testers will need to do the following:

1. Solve 3 puzzles for each level. There are total 4 levels - Easy, Medium, Difficult, Very Difficult.
2. Rate the level of difficulties for each puzzle.
3. Provide additional feedback (optional).

While I won't be able to offer financial incentives for being a beta-tester, what I can promise is lots of fun (if you are a Sudoku addict) and a complimentary copy of my book when it is published.

If you are interested, send me an email at wei_meng_lee@hotmail.com and I will get back to you. Thanks and have a nice holiday!