Kingdom Hearts: Birth by SleepFollow

Venitas is a **** /rant.

Other then that, I'm really enjoying the game, got it a few days ago, and started playing through Ven's story line, some boss fights have been a challenge, so I probably suck ._.

How are the other two characters story lines? Also how does that work, do I play through them on the same save file after finishing Vens, or on other save files?

You get a completed save file for every character's story you beat, after completing them all you get access to the final chapter.

I'd recommend doing Terra's story next, by the way. I'd be spoiling stuff if I told you what I thought of the other stories, but the game does a great job of connecting all the dots with KH1 and KH2. I expected this to be yet another crummy spin-off (I'm looking at you, 358/2 Days), but this game actually felt like it added something to the overall story and feel of the Kingdom Hearts series.

Yeah, takes a bit to get used to a new character. Ven's quite fast, Terra's a powerhouse, Aqua will leave you relying on magic a lot.