Personally, the overall concept of Maelstrom, Surges, Wild Surges and Vaults seems fine to me.
Getting better thralls, should be a bit harder (work) for you to obtain. I have yet to do a T4 surge, although did have enough ??? pieces to do 1, but my clan (3 of us) decided to do a T3 instead since getting better thralls is our main goal. In our first attempt, we got 1 blacksmith T3, 1 blacksmith T2, fighters T3 (x3), archer T3. Would have gotten a tanner T2, smelter T2, as well but we messed up and killed them the second time we fought them (woke up). We did kill the other thralls which could have been knocked out but that was intentional.
I personally harvest in the maelstorm once in a while and get 25 to 40 ??? drops a run. (Much lower than some have posted above) Its fun to fight out in the Maelstorm. You only need 400 chaos points for T3. Half that for T2 if you are just looking for crafters for your stations. Named crafters/fighters while are great to have, but not necessary when starting out. The mad rush for everyone to get names seems to be missing the point. Enjoy the game, and you will get them in the long run.
On our server, people (clans) split the cost of T4 surge, by paying 1/3rd the cost and cover / use one pad so whatever pops on the pad is theirs. So you can always arrange agreements with others to do a T4 surge and not have to pay the full freight. Granted, you may get less chances for good thralls but you also did not need to farm as many materials either. This is one way around small clans / solo players can do to do a surge.
One balance issue I could say they could adjust is one skull bosses should drop at least double a normal mob drops since they are at least twice (if not more) tougher than a standard mob. Its the only tweak I recommend at the moment with my lack of surge experience (did 2 so far).
Isle of Siptah (beyond the Surge concept) feels much easier than the Exiled lands map. Main resources are abundant on the most part everywhere on the map including gold, silver, brimstone, black ice. Coal is fairly uncommon but still found in bunches if you look. So getting started, building a base and gear is fairly easier than Exiled Lands where you had to run much farther to locations to farm a particular material. I do like the concept since it allows people to build where they want instead of near premium resource location. Also makes it easier for casual play.
There are no purges or sandstorms so no base destruction or early deaths to sandstorms when you could not find cover / have a sandmask.
Yes, getting good crafting thralls takes a bit of work, but it makes it more fun to obtain them since you have to earn them in an event than randomly finding in a location on Exiled Lands. Having all named thralls was not too hard after a while in Exiled Lands, only complication was getting the various named armorsmiths for the various gear.
Being this is early access, I am sure there is plenty more planned including more end game content for experienced players and things will be tweaked to make the experience better for all. I have enjoyed the expansion overall (even with the bugs that I hope most will go away eventually).