Upgrading from 1.9 — one thing may change. The pegasus and chevron dial spins have swapped: a gate, group or gate-dial-spin set to either now dials the other way, so set it to the other name to keep the old look. A new config.yml is laid out commonest first; an existing file keeps its own order. Everything else new is off until you turn it on, except the tunnel (gate-view-funnel, which only matters with gate-view on) and clickable previews (clickable-chat). Coming from 1.8 or earlier? Each release you skipped has notes that still apply. Installing for the first time? None of this applies. Drop the jar in and start.

• See where a gate goes, as an experiment: gate-view draws the far side behind an open gate, or clears the horizon to show it, and a big gate dialling a small one shows it down a tunnel.
• Gates ripple: gate-ripple sends rings across the horizon as something goes through and while somebody is near.
• Creatures and players in the view: mirror-show-entities and mirror-show-players show who and what is in a mirror's or an open gate's far room, as copies only the viewer sees.
• BlueMap, squaremap and Pl3xMap join Dynmap: gates, rings, public beam destinations and mirrors on each map. Set bluemap-enabled, squaremap-enabled or pl3xmap-enabled.
• Build previews have buttons: after gate build, each action is clickable. show-gate-welcome-message can tell a player where they arrived.

Full changelog