This story takes place during 3rd season. You definitely need to know the series up to that point, but not the previous book.
The story itself is pretty exciting. As can be seen from the summary, they are going from planet to planet in a test. It's very hard to stop reading, because you keep wondering how they are going to get the address and password to the next gate, and when they go through, what's going to be the next challenge. Though there are more exciting planets than others, but if we were talking about actual people, then they would be all dead halfway through.
The characterization is generally good, but O'Neill feels a bit off. On the one hand, he says these nicknames that I can't remember him doing in the show. He calls Daniel "Danny" sometimes, and Teal'c "T". I took off half a star for that. My actual rating is 3.5 stars.
What it also lacked for me was Carter. She seems to be sometimes forgotten. The guys all have something going on, but Carter feels like she's just dragged along.
Overall, an enjoyable story, exciting, and interesting. Good entertainment.