Alpha Protocol - Preview, Movie

According to this preview at PS3 Attitude, you'll need three play-throughs and around 100 hours to see all that Alpha Protocol has to offer:

There are also several factions within the game and a range of different people you can align with to ensure your experience of Alpha Protocol is different from other people. You won’t be able to complete every single mission in one play-through (which will take you around 30 hours), so if you want to play everything you are going to need around 100 hours of spare time.

Obsidian has also kicked up a GamesCom Community Interview, featuring Associate Producer Alvin Nelson answering questions and soem snippets of new footage: