I have been too busy playing int he expansion to do any kind of review but I have some time at the moment. The expansion was released on October 22nd, 2014 after being delayed from Oct. 8th. the delay did the game a lot of good. This expansion delves into the Plane of Water and the elements associated with that. The ethereal and madness specifically within the Rift universe. The first thing Trion did right is that only about 10% of the expansion is actually underwater. The rest of the world is water themed. You'll find a coral reef which has had the water removed, a place of madness beneath the ocean, and a frozen glacier in your travels. The way the zones are designed truly give it a three dimensional feel without using a whole lot of water. In Goboro Reef you'll find water walls which you can swim up to get higher areas of the zone, while in Draumheim you'll using jumping sponges to get back up to the ocean, swim through the ocean then drop back down into zone, in Tarken Glacier you'll use a series of jumping pads to traverse the zone as a giant rift splits the zone in half and you'll use the pads to jump across the ravine and down and up as necessary. This is all done without a whole lot of tedium involved once you understand the way the zones are laid out.
The entry flare, quests, and quest rewards are decent. Nothing amazing or ground breaking but they are good and more importantly they are fun. Trion also managed to make many areas of the expansion funny (especially Draumheim) without resorting to memes and other tired gimmicks. PvP has been reworked to not require separate PvP sets. In fact grinding out your currencies for dungeon and raid gear is easier if you PvP as PvP now gives rewards useful for PvE. Trion's philosophy is that "gear is gear". They seem to have succeeded in getting more people to PvP.
Trion also introduced a new system called minions This is similar to SW:ToR if you've played that. The general idea is that your minions go on missions and bring back artifacts (collectibles), crafting materials, faction increases, and dimension stuff (housing). So far this is one of the most popular features. Dungeons and raids so far are very standard fare, nothing really new here. Not bad but decent amount of fun, and very difficult right now.
There is no real bad to this expansion, being Free to Play it does have a couple of pay gates that can be overcome in game with about 6 weeks of grinding. Buying a 25 dollar collector's edition removes that gate. Their monthly sub (called patron) is insanely awesome. 50% increase to just about everything, money, notoriety, experience, all currencies earned. Well worth the 15 dollars a month.
If you enjoy this style of MMO the expansion is easily worth a look.