According to Bruckheimer, "She brings a lot of humor to it." Bruckheimer also went on to add that there is "a little romance between Captain Jack and the character that Penelope plays" too.
As previously announced, the role of Blackbeard will be played by Ian McShane. Looks like the movie is approaching its start of production date, with filming scheduled for June. Looking forward for a fresh start to the Captain Jack Sparrow's series though.