Dark Souls Combat is very flawed IMO, and that's for the following reasons:
1.
The auto-lock system: Let's say you play with an XBox360 controller. So, clicking the right stick will enable the auto lock mode, which basically guarantees that you always look at your enemy. In that way, when your enemy moves, you are auto-corrected to look him again. The problem is that there is no way to move to the left independently from the enemy. So, if you try to move to the left to avoid the attack of an(auto-locked) enemy, you will stop facing him and
the auto lock will force you to turn to the right to face him again (Consequence=you failed to avoid the attack).
Also, as I said before to set on/off the auto-lock requires to click the right stick which is a very uncomfortable "button" for often use. Even worse the unlock feature isn't instant, as it should.
Holding LT to lock and releasing for instant auto-lock whould be much more comfortable but yeah, no room for parry button then. (Also holding both LB + LT for auto-lock + block doesn't sound very comfortable either). A manual targeting system whould be ideal.
2.
The Stamina system: In Dark Souls, when you roll, attack, or successfuly block an an enemy attack with a shield, you consume stamina. That system probably exists to prevents the players from either mashing the RB attack (if you consume all of your stamina attacking=you can't roll or block enemy attacks until stamina replenished) or to play safely sitting all the time behind a shield. The problem here is that the stamina bar is too short and using the shield consumes a lot of your stamina, leading to the constant need to getting away from the fight to refill your stamina. So you block two enemy attacks with your shield, you attack to him one or two times and then you backroll and wait for stamina to be replenished, then repeat the process 2 or 3 times to kill a regular enemy, it's rather tedious.
Suggestion: Implementing 2 seperate bars, one for for attack/roll and one for shield's endurance whould probably make the trick. It would also require the player to be aware of 3 bars (health,stamina,shield) and if you count the mana bar, we have now 4 different bars in the interface, which maybe looks kinda complex. But since you don't need to watch them all simulataneous (you can't use a sword, a magic staff and a shield all together), I don't think its a big deal.
3.
Hit Detection (and the visual presentation of "being hit"): Some Poster already refered to the big hitboxes problem. There is also an issue especially related to the hit box of your character while rolling, sometimes you lose health while the enemy weapon don't touches you, or the opposite. The worst case was the battle with one certain boss from Dark Sous 2, namely
whose vertical attack did me damage while I have rolled like 1 or even 2 meters away, it was that ridiculously bad!
It looked like this(image):