Absolutely not. Control is ripped from my handling to decide combat on whether my health bar is high enough or not. Personally, I like playing with less health as it lends itself toward more tactical combat and less grinding duels of attrition. I don't mind being at low health during a fight if I can outmaneuver or dodge my enemy's strikes and counterattack; that's my combat style: weak in health but agile.
With this system, I can't survive against any old bandit chief because of this incredibly frustrating and frankly cheap mechanism. Why should the fight's outcome be decided for me? I want to win or lose based on my own merits in the fight, not on numbers. It's a step backward.
This.
It's incredibly frustrating when I'm perfectly capable of blocking or dodging, but because of the finishing move mechanic, I'm REQUIRED to keep my health at 80-90%+ at all times when fighting tougher opponents. All it does is make the already tedious task of spamming health pots that much more apparent. Those finishing moves don't check to see if you'll block or if you'll dodge, no, they initiate the moment the enemy starts their power attack and your HP wouldn't be able to survive a power attack IF it connects and IF you're not blocking. (though perhaps if you happen to be blocking AS it checks, it'll avoid the auto-kill, can't say for sure, but you definitely can't be sure you will be when it checks)
Infact, I dislike Skyrim's difficulty type entirely. I play on Very Hard and I can't tell you how many times I've faced a battle that felt like NOTHING but a game of spamming health pots. I've even gone over a hill once to be met with two mages; one a master, the other some basic apprentice or whatever. The master hits me and I lose 90% of my health, the apprentice hits me and I lose the rest. How the HELL am I supposed to combat that? Don't get me wrong: bows, summons, wards...oh yeah, they'll all do the job and I know they're there. But what bothers me is, as an RPG, I HATE not being able to pick my character type and being able to competently handle every battle. I'm not asking for mages to be a cakewalk for a pure-warrior; by all means, make them the Achilles' heal of the warrior and much harder to defeat, but I AM asking for a battle where I'm not sent to swing at some kiting mage (who yes, runs faster than me and there's really not much I can do without shouts; I would sprint attack, but enemy NPCs have this lovely habit of magically sliding to the side as you charge at them) like a [censored] as he constantly hits me with spells that take the majority of my health off.
To me, a good difficulty is where I have a chance to make a mistake via my playstyle. The problem with the scenario I named is that I haven't made a single mistake, or rather, the mistake is in the playstyle I've chosen, which just shouldn't happen in an RPG. I'm not asking to be a pacifist robe-wearing smooth-talker who never puts points into HP here, I'm asking to be a WARRIOR who puts 80% of his points into health without having to spam the ever-living [censored] out of my health pots whenever I come across a master conjurer.
Likewise, OP's example? How did he make a mistake? Again, technically he did, you could argue, but the mistake is that he let his HP drop below 80% health. THAT'S ridiculous. The health pot spam in this game can be absolutely ridiculous, and I think people have every right to be frustrated when they die because of an autokill feature being in place when the leveled enemies tend to hit as hard as they do. There should be some sort of limit on it where the autokill scene will NOT trigger unless the next hit will both kill you and your HP is below AT LEAST 30%. It shouldn't be able to trigger on someone who has 80% health; give those people a chance to dodge or block.