I've been reading Philip Reeve's Mortal engines books since high school (now 24) and since they were so amazing I've been reading the new prequel books too among the adult books I read. These prequels are good but there is just something missing for me... I just feel like the original books were more "adult" while parts of the new books are childish when they don't need to be.
That is the negative points for me which aren't that overwhelming just annoying. The positives are the characters, the chance to find out how the traction cities came to be traction cities and delving further back into the origins of the scriven etc