My Take
While access to the passages is great, you do need to print quite a bit to make use of these. It would be nice to have the option to have students access the passages online. With that said, it is one of the best sources for short, leveled text. You can use Raz-Kids, the student companion site, for access to online student text, but that requires additional funds.
How I Use It
My school uses this product to provide leveled texts for a wide variety of readers. Within each grade level, we have students reading within a range of three or more grade levels. It can often be hard to find text that is appropriate practice for this range of grade levels and Reading A-Z is a great source for help in this area. We use the passages for fluency practice on a regular basis. Students read a passage and keep track of their speed and accuracy. They then practice the passage over the course of a week and read again, at the end of the week, measuring the difference in their speed and accuracy after practice. This practice helps students to become more fluent readers in their everyday reading.