TL/DR version: I hope the development team goes back to the drawing board and reconsiders several aspects to their design and implementation.
Preamble: I am a fan of the current Epic Destiny system using spheres. I think it was one of the more interesting game systems out there. It was different, unique and had many positive effects on game play. I don't think it was perfect and it had several issues or warts if you prefer. Years ago a former member of the Development Team laid out the entire vision for Epic Levels and Epic Destinies and in my opinion it sounded like a much more perfect union of leveling and Epic Prestige Classes. The Dev added that its level of complexity was dependent upon proposed changes to the heroic systems (including Enhancements) that in the end never occurred. I do not know how far this proposed system got in to development, was it this dev's pipedream, did it fail because the complexity of changes for enhancements and prestige classes never occurred with the launch of Shadowfell Conspiracy. Yes, I just dated that discussion. In the end this discussion left me with the feeling there was so much more they could do with Epic Destinies in their spherical form. It brings up the question why were the adjustments the devs thought they could make never implemented?
The Common Class
In one breath I understand the decision to use a single common class for epic levels and cannot comprehend why it is in use. There are, and have been, many strong arguments to change that system.
I would suggest a much more in depth discussion occur on this topic, involving the player base. To me using a minimum of four classes (Arcane, Divine, Martial, and Primal) makes far more sense than the single common class, and doesn't add the complexity of the Epic Classes, expanded Heroic Classes, or other variants of that system. Using four common classes you could tie the current sphereical epic destiny feats to them while offering slightly different bonuses to each level. Primal could have wilderness lore, an HP bump and maybe 3/4 BAB, while Divine could have Religious Lore Alignment (and Fire) spell power with a 1/2 BAB.
The Pigeon Holing Design Conundrum
In the old design Twists were a great enabler of heterogenous character design or build variety. That system didn't turn bad builds into top tier builds, but it allowed players to play lower tier builds and either reinforce strength or lessen weakness allowing them to play their way.
This new design doesn't have that flexibility. If you are a solo player and would like to twist in healing you now need to not only dedicate one of your three trees to it, you have to spend a fairly substantial number of points for things you used to twist in.
Many of the new tree designs are very specific in the playstyle they are aimed for. If you are a TWF Cleric or Bow Wielding Paladin or a Mechanic Rogue or any number of dozens of other playstyles where are you going to spend your points. That new Razorclaw Handwrap wearing barbarian that is a new iconic class, well you don't truly align up with anything in the new Epic Destinies and you are out of luck.
Grand Master of Flowers?
New/Casual Players vs. Experienced/Hard Core Players
I would argue that at least to me it is easy to see where significant design changes were made to appease the various groups. Everyone of them is a head scratcher in terms of game design. All you are doing is upsetting both groups of players without effectively dealing with the power gap between both groups.
For new players the old system was confusing and lacked in-game tutorial. There were many options for them to make poor choices. Epic Leveling was a slow grind. The Twists allowed these players to play their way and enjoy the game.
For Experienced players too much time was spent in off destines grinding out Epic Past Lives that slowed their grind down.
Level Gating vs. Front Loading vs. Point Expenditures vs. Quests or Wilderness Adventure Areas. This is a whole conundrum of problems. In the end I think even more experienced players will use Wilderness Adventure Areas to quickly earn XP in epic levels, meaning even less of the Epic Content will be run. In 15 to 17 hours of dedicated play 5 players can earn 7.5 million XP without a pot. Throw in a slayer pot and that gets faster and throw in a XP pot more XP.
I think that it is casual players who are feeling the biggest disadvantage in the new system. Experienced players will adapt and move on, casual players for a myriad of reasons cannot make those same adjustments. They don't have the gear, the bonuses the past lives give characters, the know how to adapt their game. It may add a small handful of hours for an Experienced Player to level up a character for 20 to 30, it will take about 15 to 20 more hours for the casual player, on top of it taking four to ten times longer already.
In the end I don't think what we are getting are better, only different. Under the concept the devil you know, I see more warts and pitfalls in the new system. There is going to be way too many players frustrated by the overall philosophies behind the changes. The problem is I like many other veteran players will adapt and move on, but for the those casual players when they adapt and move on it will be to a different game.