The basic idea is that the movie will highlight the fictional character based on the real person known as "Vlad the Impaler" before he became a vampire.
According to Sci Fi Wire:
"The film will show Vlad when he was still vital and will explore the fact that he's considered a hero in Romania for fending off the Turks."
Maybe at some very early point Vlad/Dracula was a "good guy", but I'm certainly hoping that they show his descent into evil in the movie. After all, he did get the catchy nickname "The Impaler."
Source: Sci Fi Wire