Critics who caught an 18-minute preview of James Cameron's conversion of "Titanic" to 3D say it looks almost as good as a film originally shot in 3D.

20th Century Fox

ourteen years ago, James Cameron's Oscar-winning epic Titanic first introduced us to Leonardo DiCaprio's Jack, who froze in icy waters as the unsinkable ship sank, and Kate Winslet's Rose, whose heart went on and on via YouTube and Netflix. Next spring, the beloved/ridiculed film will return to theaters painstakingly converted to 3D at a cost of $18 million. Cameron recently previewed 18 minutes of the 3D footage for the press and, while films rarely dazzle when a third dimension is belatedly tacked on, commentators say the Titanic 3D conversion "truly impresses." Here's why:

1. Cameron's film is unusually well-suited for conversion
Typically, "I absolutely hate post converted 3D," says Peter Sciretta at Slash Film. But this "looks almost as good" as a film that was natively shot in 3D. "If I had never seen the movie before, you would have been able to convince me" that it was originally shot in 3D. It doesn't hurt that "Cameron's cinematography is usually slow and steady and wonderfully composed for depth."

2. 3D heightens the emotional intensity
The 3D is especially evocative during the sequence in which Jack is trapped in handcuffs at the bottom of the ship, and Rose rushes to free him, says Adam B. Vary at Entertainment Weekly. "As she raced through the ship's empty bowels, water rising with every passing second, the 3D really did give me a greater feeling of how alone she is in those long and deserted hallways." And "watching the water lap against the frame, always threatening to spill into the theater, certainly helped add to the sense of anxiety."

3. 3D aside, it'll be great just to have Titanic back in theaters
Watching Cameron's preview in a movie theater was "a reminder of all the great details in the picture that get lost — even on a big screen TV," says Gregory Ellwood at HitFix. "The detail in the production and costume design was immense." The striking chemistry between Winslet and DiCaprio also really comes across when the film is in theaters — in a way that it just can't "on a cable repeat on TNT."