One of the things that has been revealed as a result of this past weekend's GW2 Press Beta event is the screen with the number of character slots: 5.

Guild Wars 2 Guru thread discussing such: Character Slots Revealed
I believe 5 character slots is what was reported a few months ago and something I'm (generally) okay with, assuming character slots will be available from the in-game store from the start. In that case, it looks like I'll be buying about 3 extra character slots - at least - on Day 1.
______________________
