Which one did you do? I chose Assassination, because I've been that spec for a
long time. I first went that back in vanilla during BWL.... Man, that was crazy on Vaelastrasz with an effective infinite energy!
Anyway, I thought the quest wasn't too bad for Assassination. You had to sneak around Stormwind for the majority of it. So, it was mostly just using distract and sapping guards. They even borrowed a feature from Assassin's Creed where crowds (marked with a glowing circle) would put you back into stealth.
Although, apparently, Assassination just isn't as good as "Outlaw". Ugh, speaking of that... I really don't like that name. Outlaw just seems so darn cheesy. While that's just a minor quibble, my main complaint comes from the dumbing down of rotations. I complained about this during the beginning of WoD, and they've removed
even more abilities! Now, to be fair, I didn't select any of the abilities that you can get via talents, so I might need to select those so I don't fall asleep while playing. I mean... there are literally only three buttons to push right now: Mutilate, Envenom, Rupture. (You can also Garrote to start a fight.) So, I might end up selecting Exsanguinate as it's at least a 45s cooldown ability (speeds up bleeds).