Is borderlands free roam

Answer 1

No, it is mostly linear. You start at a 'hub' location that leads to several smaller ones, and eventually progress to a second hub, then a third, etc. Movement across each map is mostly unrestricted but enemies in one part may be a much higher level than the player, forcing him to work through lower level areas first, hence the linear progression. Generally there are also physical blockers preventing access to new areas, again meaning there is not much free roaming about it until you've reached a high level, unlocking all areas and able to deal with the enemies there.