Slum Online is an interesting novel, in that it's an idea I'm surprised hasn't been done before. The concept of a great quest inside a video game being the main focus of the story while reality plays out in a more mundane way around it, you would think with the rise in popularity of video games in the last decade that this would be the sort of story more people would have come up with.
That said, the novel is interesting in that it's actually rather deeper than the plot description lets on. The classic movie buffs reading the novel will instantly catch all the references to the 1961 classic "The Hustler" staring Paul Newman. If you haven not seen the movie, then you'll actually be missing out on some of the nicer details in the novel. They draw so many parallels between our protagonist's quest to find the infamous Ganker Jack and Fast Eddie's desire to beat Minnesota Fats that they flat out mention the movie on a few occasions. Comparing the two stories is part of the fun of the novel.
The book was a nice short read. Entertaining, but with many faults. While the story was deeper than I was expecting, some chapters seem to end rather abruptly and then suddenly two weeks of time will pass in-between the chapters. Also the constant use of "FX" as describing sounds in the real world got annoying. I understand that it was supposed to show how the main character felt more at home in the video game world, but it still was overdone.
For the American release there's a bonus short story after the novel, from the point of view of a side character. It's a nice little addition, and to be honest, in some ways it's better than the actual novel. It flows slightly better and ends on an interesting note that makes the reader consider how the story will truly end.