I've been enjoying the new zone, it reminds me almost of an adventure pack, then just a 'bit of content'. I rode around the perimeter, just to see how big it was, and it took better than an hour.
It's not a huge addition, content-wise as it's really for the 50 level players, but speaks well for TRION and their commitment to continually providing great content and listening to their player base.
The questing is doable solo, but really feels designed for grouping as the mobs are in general level 52 or elite. Do a few quests or invasions there, Stillmoor and Shimmer Sand feels almost easy!
The dailies (there are quite a few scatter around the island), involve defending the Sourcewells , in the form of Onsalughts, against invasions. Fortunately there are NPCs there to help and defensive and healing turrets powered by planar charges (hmm now we know why we get more with our Planar Attunement!), but there are plenty of planar anomaly crystals to recharge depleted planar charges scattered around Ember Isle.
On my tour, I did discover a giant waterfall hole - reminiscent of Stranglethorn Vale post Catacylsm - a giant hole, the Dormant Core - only this one was full of elite dragon cult and other mobs. There is an achievement, Cliff Diving into Dormant Core, and fortunately a crystal that will return you to Ember Watch.
Above it I found in Ember Watch, The Keeper's Quartermaster. New recipes and other goodies (rep needed) as well as an armored Ash Strider. Ember Watch is the neutral quest hub for both factions.
Ember Isle has some interesting Achievements such as:
Dancing Delivery - you have to dance on specific mail boxes throughout the zone, including two in the oppositions towns. A rogue with sap helps quite a bit.
A ton of new rare mobs, artifacts galore, new rep to grind, etc. Defeating the four invasion bosses (In Golden's Grasp, Fires of Rebirth, Ithkus' Rise & The Seed of Change) earns you a wonderful hat!
There is also one of the Rift puzzles for this zone, Emerald Enigma, which rewards you with an adorable new companion pet, Bernie
The new instance - Caduceus Rise
is fun. Nothing super new as far as boss mechanics go, the one puzzle, does require a bit of thought - don't do it when you're tired! - but we did both upper and lower before any of the "how to" guides came out, so lots of fun learning the mechanics. Caduceus the final boss, can be a bit buggy still, and we've actually given up once - too many people to tired and frustrated with the buggy fight. A master mode combining upper and lower is expected out in an upcoming patch.
All in all, we're thoroughly enjoying the new content, but tend to go in duos or a group - its more fun and definitely easier!
Rift Zam's guild to Ember Isle : http://rift.zam.com/en/zone.html?riftzone=676
Here's a great link: Orientation to Ember Isle
Sourcewell Info: Onslaught, Sourcewell and You!