USA Today Everyday Sudoku: 200 Puzzles from The Nation's ... (ISBN 0740769189)

Good collection of Sudoku of varying difficulty:
A co-worker turned me on to Sudoku a couple of months ago. He does the USA Today Sudoku daily. I picked up this collection recently. The book starts (as do most such collections) with the almost-standard Sudoku tutorial. The puzzles are rated from one to five stars (easy to hard) for difficulty (65 one-star, 45 two-star, 50 three-star, 20 four-star, and 20 five-star). The star ratings seem reasonable. In every collection I've seen, I have found that there will always be a few easy ones that are hard because you missed something staring you in the face, and a couple of hard ones that are easy because you got lucky at just the right point. The ratings here seem pretty accurate. The grids are decent-sized; not jumbo, but not tiny, with one puzzle per page. In addition to the usual heavier lines between 3x3 cubes, these puzzles have alternating cubes shaded gray, which makes it very clear where the cube boundaries are. The gray is a little too dark for my taste (especially if you don't have a dark pen or pencil). The numbers are bold and large. Unlike some collections, these are all traditional Sudoku -- no variants such as Monster Sudoku, Sudoku X, Killer Sudoku, etc. Also, unlike a lot of recent collections, the givens are actually placed symmetrically (in fact, this book was the first one that I've purchased that actually does use symmetric givens throughout). All in all, a good collection of Sudoku. By the way, if you're interested in an overview of Sudoku, including history and mathematical background, I recommend the Wikipedia article on Sudoku.