Times of Trouble is at least as good as the two earlier Blackford books. Just like in the first two, the characters are great (and Jade, the superhuman girl from the future, is very cool), and there's lots of fast action, but it's also very realistic - not like the T3 movie.
There's all sorts of time- and space-travel across diferent time-lines, with John and his friends attacking the Skynets, and the Skynets have a heap of mean new tricks. The time-travel stuff is complicated, but interesting, and it's explained well.