I can forgive the retread stuff so long as it sets up an interesting trajectory for future movies.
I really didn't expect to see another f'n Death Star with a fundamental weakness. :facepalm:
"This part seems important...let's have...six guys guarding it."
While I agree that the "there's always a weakness" trope is a bit tired, you have to give the bad guys a little credit.
The Death Star had a critical weakness, but it required someone using the Force to exploit it (and remember, as far as the Empire was concerned there were essentially no Jedi left to do so).
Death Star II had no such weakness, but wasn't finished when the Rebels found it and the shield generator was external.
Starkiller base had an internal shield system that could only be circumvented by doing something insane (using a hyperdrive to approach the planet), and the "weakness" the rebels exploited was actually pretty strong. Despite being taken completely by surprise without the help of their shielding and without any fighter cover, the First Order still successfully defended the weak spot (and the weak spot held up to heavy punishment itself) up until previously mentioned crazies that knocked out the shield also managed to blow a hole in the structure. It then took an amazing pilot to fly through said hole and fire several salvos of perfectly placed shots to destroy the base. What kind of engineer can predict that ####?