The basic rundown is that attributes have been given new utility, to allow people to tweak their builds for their own personal goals. Points in Body will add addition armor for those concerned with survivability, points in Mind will bump up the damage of Logos abilities, and points in Spirit will increase the likelihood of delivering a critical hit. In addition, the health levels for all characters is being bumped up to better emphasize the role of healing in combat. The way it works currently, if your armor is stripped away, you're basically dead in the water -- it only takes a few good hits to deplete all of your health. By making the health bar bigger, healers actually have a chance to apply their skills before their buddies wipe.
1.4 isn't on the PTR just yet, but Sage is encouraging people to try it out while it's still being tweaked so they can get some good feedback on it.