I really loved the Raiden episode. The gritty real world feel works really well with this story. Even if it is really creepy. I've seen several takes on the 'wrongfully stuck in an insane asylum' trope before and it always winds up being really dark. The episode really doesn't pull any punches (heh, Mortal Kombat pun) with the content and really goes all out to create a dark and terrifying environment to introduce the character. In short, it creeps me the hell out, but I love it anyway.
Episode 6:
I was also pretty impressed with what they did with Scorpion and Sub Zero. Some might argue that part one drags a little, but they clearly wanted to take the time to set up Scorpions character and show him as he was before fully embracing his role as MK's token tortured soul.
Episode 7:
Episode 8:
Only two further episodes remain, hopefully they will maintain the quality we have seen thus far.