I can't take James Franco seriously as a villian

That's not 100% true. As the story was about four girls going on Spring Break, who then meet up with Alien the character Franco plays, as such, he can be seen via the public at large as the main villain to the girls (as in appearance, lifestyle etc.), even though Gucci Mane's character is the main rival in Franco's world (Mane was the teacher, and Franco the student), plus as we later find out that two of the girls are clearly psychopaths in the same league as Alien.

Furthermore, once the character Faith (Selena Gomez) leaves, it's essentially Alien's movie.

Those who can't take Franco seriously as a villain in this new movie, have clearly never checked his movie profile, because any guy who can make a 2010 short film called Herbert White, with Michael Shannon, which dealt with necrophilia and was subsequently banned because it was deemed too extreme (remember all the horror movies that play but this was deemed too extreme), can play a villain.

As well as, his new movie coming out soon which he directed called Child of God, which further deals with necrophilia, means somewhere in his mind, he can be creative enough to play a great villain depending on the quality of the script and director in charge plus in my opinion Franco is one the best actors of our generation, so this new role should be easy.

Oh, remember also when Spring Breakers cast list was first announced, everyone stated it was too bizarre to work, with Disney girls, an Oscar nominated actor plus Harmony Korine, and it worked perfectly with some audiences (now a cult classic judging by the number of people who wore costumes in response in particular to Alien for Halloween or masks like the girls) that they're even now campaigning for Franco in regards to an Oscar nomination, which I hope he gets.

Yes, this movie will also prove that Franco is the best thing in the movie, it seems that he is having a lot of fun with this role and I'm looking forward to Homefront, it should be great.

He did.