Carl has a summary here of all the new free features:
https://www.carls-sims-4-guide.com/patch-notes-island-living.phpThe fishing skill updates are pretty big. Seems at first glance like a lot has changed:
Fishing Additions:
Brace yourself, we’re about to cast you into a deep dive…
We added several new interactions to allow players to fish in different ways and interact with other Sims around fishing activities.
Sims can perform a few new Fishing-based socials to gain useful info (via UI TNS/Notebook) and push NPCs to Fish.
Fishing is now joinable.
Improved fishing interaction tuning and autonomy to make the interaction more efficient and fun.
Upper skill levels now provide more meaningful rewards, with new Interactions added to Fishing skill levels
New high skill cast interaction “Angle for Big Catch” increases chance of getting rarer fish.
New high-skill VFX visuals on Rare fishing spots.
Ability to now “Mentor Sims in Fishing.”
Fishing UI has improved information, including Notebook info with Bait information.
Tuning for fish that can be caught is unique per world & more fishing spots added to some of our previously shipped worlds.
New bait preference system applied to most existing fish that modify catch chances.