Full slide protection is good against interior blitzes and twists/stunts because regardless of defensive movement, the assigned blocking gap does not change. Despite its uncomplicated nature, full slide protection is not commonly used as a base blocking scheme in today's NFL because it forces the running back to block an edge rusher. Many teams prefer to keep their backs away from experienced/dangerous pass rushers because backs tend to be poor blockers and assigning backs to interior linebackers gives them a better chance to release into a pattern if their assignment isn't rushing (i.e. "check-release").
Outside References
1) Calling your full slide pass protection