Since I'm also playing the new berserker and my character has reached a similar stage in the game, some additional comments.
By the way I'm playing normal / roguelike. Died once, to a forge giant with cleansing flames who dispelled my Unstoppable. (Resurrected with blood of life.)
Overall, this character is one of the strongest I ever played. For example I was confident enough to rescue Melinda while playing Roguelike (never did that before). Power creep did happen imo.
Or maybe it's just because of the weapon I found. Borosk's Hate, a new artifact 2hander. Pretty amazing weapon. Found it randomly just after the Master. Stats:
Base Power 60-96
+10% crit
+10 str, +5 dex, +15 con
+0.2 technique / two-handed maiming
On hit: 25% chance of a free extra hit (!)
Berserker Rage has come off to be a bit of a nuisance due to the loss of hitpoints every turn.
In my game I barely noticed the drawback. As long as your natural regeneration (from Fast Metabolism and items, including items that raise healing factor) is decent, it doesn't have that much effect, in my experience. Honestly I liked the old talent better, though. A trade-off that is bad in the early game but good in the late game is more interesting.
What was the reasoning behind the change in design? If it was to prevent beginners from using this talent too early, then you could also solve that problem by simply making it the 4th talent in its tree.
1/5 Executioner hasn't really served much purpose since really entering the late parts of the game, and 2/5 Shattering Blow has pretty well just been outclassed by the damage my character is doing
I raised Executioner to 2/5, shattering blow to 3/5 and I'm using both fairly often, also now in the endgame. Executioner deals massive damage on bosses that already have been hurt. Shattering blow is very handy for dispelling damage shields.
One talent I need to mention is
Relentless Fury. This talent gives you almost unlimited stamina. It
also raises your attack speed and movement speed by 34%, for a whopping 9 turns (at 5/5). That's massive. A 34% attack speed bonus is almost a straight 34% damage boost. One of the major power creeps in the new berserker.
Please reconsider this talent. The stamina boost alone already makes it a very strong talent, better than many existing talents with that purpose. With a 34% attack / move speed boost on top of it, it's just broken. The optimal way to play with it is probably to exhaust your stamina pool and then activate it, before any fight.
My character has only one weakness, and that's being Disarmed. Being Disarmed is such a concern that even a talent like Unstoppable is now laughably weak and Tactical Questionable to use because of how often Disarm pops up.
Disarms from acid runes are indeed a real pain in this version, I agree. I hope that the fact that Disarm Immunity doesn't help against them is a bug and gets fixed soon. Even if that's the case, it will mean that Disarm Immunity becomes priority number 1, 2 and 3 for equipment choices, which still isn't great. Honestly I hope that acid runes are nerfed or at least changed. This just isn't fun.
Although that's a problem for any melee class, not just berserker. So back on topic.. My berserker is still (ab)using unstoppable all the time. But that's because it's a Shalore. Other races really do need to be cautious, I guess.
I'd like to reiterate here that if Unstoppable is going to be changed, it would be good to consider that this talent is currently giving a major advantage to Shalore. Reducing the duration would do no good, because it would only make this advantage bigger. I wouldn't like to see Unstoppable gone, but I think it would be an improvement to make it less absolute.
This is why my solution would be to let Unstoppable temporarily triple your max hitpoints. This would have the following consequences:
1. You could still do crazy things like jump into the middle of a group of enemies (especially when playing Normal mode).
2. It may sound overpowered, but compared to being completely immune to damage (as now) it is still a big nerf.
3. Resistances, HP, armor and so on would all become relevant while unstoppable.
4. Because of that, Shalore would be a little less of a dominating choice. For example dwarves have more hitpoints and that would become a real factor again.
5. The rules could be simplified, as the massive heal at the end would no longer be needed. Also, the special rule for the interaction with the berserker talent could be dropped.