This is Hollywood formula action/sci-fi at its worst. You can almost hear the movie execs being sold on this one. "Well, it's kind of like Armageddon, except it occurs at the middle of the earth, and it's also kind of like..." Basically it borrows scenes from every disaster/action movie you'll ever see.
I don't blame the actors. The cast is filled with decent talent for the most part. They didn't have much to work with given the cartoon-like script and paint-by-numbers storyline. This movie also completely misses the point of the "science" in sci-fi. In order for a sci-fi story to work, the science aspect has to at least seem somewhat plausible. Anyone who has ever studied anything about computers, physics, chemistry, or geology will find themselves laughing hysterically during this nonsense.
Even the special effects are rather weak. It seems no one was really sure how to depict a journey to the center of the earth in a space-ship like vehicle. So we end up with a lot of shots where the ship seems to be traveling through a vague, nebulous electrical cloud. I won't even discuss the laughably bad destruction of Rome, Italy sequence.
I know some will defend this as a mindless popcorn flick. But how many times can we watch the same old story unfold? How many times can we watch the same cookie-cutter characters go about their predictable business?