I shudder in anticipation of "original" Latin dialogues.
Nobody exactly knows how Latin was pronounced (e.g. philologists are still fighting over the c/k issue) and you of course cannot speak a dead language without an accent. So basically it will sound like Latin to British/US/Canadian/Australian people but for Italians, Germans or any other folks who don't speak English as a first language (that includes me
) it WILL sound terrible.
The second downside is that this movie may make people actually believe that Latin was spoken with the same pronounciation the actors use and spoil their sense of history like movies already did with several cultures.