Aliagor

To start off I completed E2EE 3 times, one normal solo run, one team peaceful run and one solo skyblock run. They all should add to ~1000 hours of playtime combined.

Quests:
Quest lines that have been reworked/improved in E2EE compared to E2E are really good. Best example of this would be Thaumcraft quests, original quest line from E2E was really lacking in quality. Quest rewards have been rebalanced but they are still mainly loot boxes.

Custom ore processing:
Ore processing has been improved mainly due to buffing the "Refining" infusion enchantment from Thaumcraft. There is more steps including magic to the ore processing to get even better yield or chance for byproducts but in most cases first step is enough. I used next steps only for one type of resource that was quite tricky to get.

Computer mods:
Some of the mechanics like printing blocks from computer mods are needed in order to progress. They are all explained in tooltips for player that might not have required programming knowledge.

Peaceful mode:
While this mod is not super hard it comes with really nice features for other modes. If the game is beatable in peaceful mode you can craft loot from mobs and bosses which provides another option to progress. For gaia spirit can be crafted and automated if you do not want to fight the boss.

Mechanics variety:
Modpack developer nerfed "Mainstream" options and mechanics like Mekanism Ethylene power generation and Angel Ring for example. This encourages player to find options from other mobs. Good example might be flight, getting angel ring requires a lot of EU2 power and NC:O irradiation which might seem like a "scary" mechanic. This item is not super expensive but requires some knowlege to be able to obtain it. Other options for flight might be Beacon with custom block for secondary effect (there is block that will give flight and you can add block that will make the beacon effect work for single player in whole dimension), final armor from Thaumcraft addon progression gives flight as well, you get access to semi-creative flight in Thaumcraft even earlier. There is more options I just listed ones that I used.

Skyblock experience:
Early game of skyblock is probably one of the most unique ones I played. For ore gathering you can use standard Ex Nihilio sieves but they give only a few types of resources and processing drops from them require in world fluid interaction with seared stone fluid. Iron can be gathered from trees and gold can be obtained by turning pigs in pigmans. After you have ore generation done and enter mid-game the experience is pretty simmilar to the normal run, you will have to use more expensive skyblock recipes for items that you would find by exploration.
Late game skyblock is where the difficulty starts showing. To reach end goal in skyblock you have to use most of the mechanics in modpack. Most notable QMD, Bees, NC:O. In normal run you could skip hard parts by exploration but in skyblock you have to take the long harder route.

Exploration:
Exploration is super rewarding in E2EE. The rewards are mainly tied to exploring other planets using Advanced Rocketry. You can find fluids to pump out using pumpjacks or some pumps if fluids are placed in world. Planets also can spawn blocks that are needed in progression for some mods. For example you can find NC:O fuels, QMD liquids or EnderIO liquids. Most of these things would require big setups but some of them can be skipped by exploration.

Magic mods:
Magic still feels kinda left out like in E2EE. Thaumcraft is way better included in progression than in E2E but Botania, Astral and BM still don't have that many uses so there is no reason to create powerful mana generation or a lot of max tier blood magic altars. In recent update I have not played BM is getting more uses so hopefully this will continue for all magic mods.

Development:
Modpack developer is active on Discord and is open to suggestions. If you find a bug or some mechanic that feels grindy you can reach out and possibly contribute to improving the E2EE experience.

Performance:
Never had any issues and modpack developer is constantly trying to improve the preformance. This also comes with some downsides because convienient but laggy options (IC2 ejector upgrades for example) might get disabled in future updates to improve servers performance.