Mmmm ... my 8 yr old DS got this subscription as a gift too and although he just adores reading, he is not overly taken by it. I really do not know why but he had previously had a subscription to national kids geographic and he preferred that. It is quite serious (although that does not normally put DS off!) whereas kids geographic was a bit more cool I suppose. I also get the feeling that it may appeal more to girls - but I stand to be corrected!
We had it for a year or so. My dcs were interested some months and then other months they couldn't find much in it to catch their interest. So it was a bit patchy. After the subscription ran out, we switched to First News which they much prefer. We also like How it Works. Have 2 dses BTW, who are 11 and 8.