If you are actively using 3.5.5 and it works well for you, —especially if you are in the middle of a project. Enscape 4.x changed the asset system, material editor interface, and licensing model (Chaos license instead of Enscape-only). Do not upgrade mid-project.
: Over 50 new high-quality 3D scanned people assets were added to diversify scenes. Enscape 3D 3.5.5