At first I was about to take this information seriously, but then I actually did read the writing.
"The Dante of DmC is a young man discovering and coming to terms with what it means to be the child of a demon and an angel".
He's coming to terms with what it's like to be the child of a demon and an angel. Angels are more human than demons are, they can choose to display human emotions (They have the ability to love and care and cry). Demons aren't meant to hold kind human emotions, as Devil May Cry states lots of times. Demons hold impure thoughts and don't care about their actions, they seek to destroy what's around them and cause harm to humanity because it does not belong to them. What makes angels more human is that like us, they have the ability to choose what it is they want. It's like Sparda, he stopped and realised he didn't want to hurt humanity. He rebelled against his own kind. He did something that demons wouldn't usually do, he made his own path and actually started to feel emotions that he wasn't really meant to feel.
Dante in this is coming to terms with his demon and angel powers. It does not state that his mother was a full angel now did it? And would a full angel really mean no human side? We don't know how Ninja Theory are defining what it's like to be an angel, so we can't say "well it just makes Dante half angel". And also not to mention, when Sparda was wandering the human World he was becoming more human. So he wouldn't of been a full demon when he had the twins with Eva. This would still mean that Dante would have a human side to him (In some way, shape or form) So no, I don't believe this confirms that he's half and half.
I think we all know Ninja Theory mentioned that Dante still has a human form. They mentioned this in an interview after that information was posted on the website (I believe).
What I think is Dante will be in his human form until he activates his 'devil' or 'angel' trigger. He could be more human, more demon or more angel. But to me, he still is human also. Whatever one he is the most, we won't know as of yet. I'm going to think he's more demonic this time around, which to me would make sense.