each episode costs 400 MSP. i know for the PC version you can pay a flat rate for the 5 or 6 episode pass that saves you a few bucks, but no such luck on xbl arcade from what i've seen.
i've played through the first two chapters, and i'll tell you, it's addicting. You get roughly 2 hours of gameplay (maybe more if you don't rush sometimes like I did) per episode, and it's totally engrossing. Almost every choice you make has repercussions throughout the story. Decisions I made in episode 1 carried over into episode 2 by way of characters remaining and dialogue.
they also made a key change that I absolutely love to up the ante a bit in conversations. For most of your conversations, you have 3 choices that are dialogue and one choice that is silence. There is also a timer- the more frantic the situation the less time you have to decide what to say. If you are late or don't choose, you use the non-answer silence and THAT even affects how characters perceive you.
I love the game. Minor disclaimer though- don't expect to be doing a ton of combat, and the combat you DO do is going to be point and click for the most part. Just wanted to throw that out there.
fans of the series will love these games though.
THE Luke Kuechly Super Collector