I started playing this again over the past week (I'm working 12 hr night shifts and frequently am not busy). The Crystal Cove area has been open and I have been having a blast running it. I've gotten to where I can solo it 9 times out of 10, and managed to get 330 crystals once.
It got pretty intense at times... At one point, the main "boss" came up to the top of the ramp, along with 1-2 other "mini-bosses" and several wraiths... They killed me, my hireling, and all of the kobolds... but I'd already gotten the 100 crystals so I still "won".
It was hard on my equipment, though... At one point, everything I was wearing was broken.
I definitely was spending more in repairs than I was getting out of it...
It was definitely worth it, though. You can craft/buy some really great gear with the green gems you get as a reward, and it was tons of fun. I did a few runs with a guy, and it was way easier with two people. Even after crafting/buying myself a set of armor and several skill boosting hats (probably costing around 1000 total), I still have over 1600 green dragonshards.