Path of Exile is always being updated with new stuff but the Forsaken Masters update had me try it again and more content always makes for a better game. I hadn't seen the Vaal Gems - corrupted gems that require enemy kills before you can use them - yet nor the randomly placed random dungeons, so there's a lot of stuff in there to digest for me. That being said, I'm having a blast by playing it again.
The titular masters add a lot to the game, you find them randomly and they offer you quests that differ for each master - some might ask you to defeat them in battle, others might want you to kill a boss but leaving his minions alive, one even asks you to bring a spirit that causes a bunch of bad stuff to happen through a cave - by doing these quests, you level up your reputation with them, allowing you to buy items and get crafting tables for your hideout. These tables allow you to get specific buffs you want on your gear and doing the quests is a fine way to get experience.
There are two new leagues you can create your characters in, Rampage and Beyond. In the rampage league, killstreaks activate effects like shooting projectiles around or summoning ghost weapons to attack your enemies - I wish it would say what the effects are specifically - and in Beyond, killing enemies has a chance to open portals, summoning stronger enemies in - and this effect can happen when you kill these enemies as well. I only wish that Beyond mode wasn't hardcore-only, having this cool effect only on characters you try to be more careful with is a bit weird and you can't mess with it too much.
To conclude, this game is one that changes enough to be fresh whenever you quit and come back. It's a pretty great action-rpg and it continues to add on top of all the things you could already do with these masters, new gems, new items and new dungeons, I recommend it 100%