This release comes with lots more bug fixes, a big overhaul of Cities, a lot more usability tweaks in JoshariasSurvival, and then some.
Full engine changelog: http://jenkins.terasology.org/job/TerasologyStable/58/
Issues / PRs included: https://github.com/MovingBlocks/Terasology/issues?q=milestone%3Av0.54.2+is%3Aclosed