You can also read this review on my blog. 
 In short: Vortex by S.J. Kincaid is an excellent sequel that ramps up the intensity in the plot while still maintaining the fun and hilarity of its predecessor. 
 I was incredibly eager to return to the incredibly cool and imaginative world of S.J. Kincaid's Insignia series after reading and loving the first book last year. And thankfully, I loved Vortex just as much as Insignia! For those who don't know, the Insignia series is about fifteen-year-old Tom Raines who is recruited by the Pentagon to fight in an intrasolar World War III thanks to the help of a chip that has been inserted in his brain that allows him to remotely control fighter ships in space. It's AWESOME. 
 In Vortex, things aren't very much different from Insignia. As with Insignia, there are plenty of seemingly pointless - but incredibly fun - scenes with the simulations. Tom and his friends get up to the same kind of hilarious shenanigans. S.J. Kincaid's signature clever humour and inside jokes are also present again, much to my pleasure. The main difference is Vortex is a bit darker and more political than Insignia. A more concrete villain has developed, Tom is having to be serious about his future, and a hint of rebellion is forming. And all this is managed without sacrificing the fun and hilarity of Insignia. 
 Possibly the thing I was most looking forward to in Vortex - even more than the highly imaginative and cool world building - was the return of the gang: protagonist Tom and his best friends Vik, Wyatt, and Yuri. THESE GUYS. They have got to be my favourite bookish group of friends ever (after the HP Trio, obvs). I love each of them individually, as well as part of the group. They are very loyal (though they do occasionally have disagreements) and are incredibly playful and teasing with one another. They feel like real life friends to me! 
 Tom is a hard person to love, considering his many, many faults, but I do like him overall. His arrogance and stubbornness often border on stupidity, but his intense loyalty to his friends and his refusal to play by corporate rules are truly admirable. His highly immature antics are equal parts exasperating and amusing; he is just a fifteen-year-old-boy after all and I think a very realistic one. One that has to face the music in Vortex and learn not to be an arrogant ass all the time. Tom is a very memorable character and I credit S.J. Kincaid with coming up with a non-stock protagonist. 
 I had the same issues with Vortex as I did with Insignia: The story was sometimes slowly paced and bogged down with exposition and technological jargon that made the reading a bit rough. But overall, Vortex was just as much fun as Insignia while also ramping up the intensity and seriousness of the plot. Dystopian and sci fi lovers who like male protagonists and plots that aren't super romance-heavy would love this series!