I was able to solo every boss but two in Avalon as a fire wizard with Wintertusk crafted gear.
I would say that (at least for me) it was challenging but not insanely difficult. My guess is that when you add in the new monstrology system it would be even easier to beat as you can toss out an extra minion to help deal out the damage.
It's not necessarily hard, no. But the bosses are definitely a level up. Yes, they do cheat. Mobs are fine. You should be able to solo most of it if you know what you are doing. Tip though, when you get to Jabberwock, pack a lot of heals and go in with a lot of people, preferably high level. He is probably the worst boss in the game. The ending fight was ridiculously easy, I did it with just another fire at my level and me (storm).
Avalon isn't challenging for the most part, besides a couple hard bosses here and there. If you find yourself having difficulty figure out whats wrong immediately, because Azteca onwards things begin to get tough trust me. Even though most of those worlds have been nerfed a bit, and some a lot.
To my knowledge, Avalon has been pretty easy. Avalon has had its ups and downs, but the overall world is beautiful. Avalon has a great design and lots of neat, new species. The world was beautifully executed and the design is probably my favorite! Avalon hasn't been too hard, to be fair it has been a breeze. I am a balance wizard, and I have the Zafarian crafted gear with Wintertusk crafted Athame, Amulet, and Ring. They will be a great help! Level 76 gear is also a great boost as well as the Courtly Dirk & the Triskelion Band. I hope that this helped! If you have more questions come find me in the Ambrose realm.
Hello, I've not made it too far through Avalon, but so far, it's not been too hard. I'm a level 74 Balance and it's not been much of a struggle. A few things I suggest would be to get someone to help you on some of the bosses, and get someone to help you on defeat and collect quests, which have been a bit tedious for me. Good luck going into Avalon!