- You can shoot arrows in peoples heads, hide, and they'll just go back to standing around as if nothing happened, with an arrow stuck in their head. Not only does this look and feel completely stupid... it makes bows and daggers too easy to use. Once NPCs have taken damage from you, they should stay alert until you either kill them or leave the zone for more than 5 to 10 minutes. Nobody, not even a fantasy world NPC character, would go back to business as usual after taking a freaking arrow to the head. It feels stupid, glitchy, unrealistic, just way off of what you'd expect from a game of this caliber.
- You can slit an NPC's throat right in front of his buddies and they won't notice and much less care. How would you react if that guy you just talked to a minute ago is laying on the floor with his throat cut open as you come back on your patrol? NPCs in Skyrim just don't care they'll walk around the corpse completely oblivious to what happened.
- You can literally stand right in front of NPCs, they won't notice. It would be okay if you actually used invisibility, but its not okay when you're not. No matter how high your stealth and how large the level difference, if you walk right in front of an NPC it should detect you. Otherwise sneaking is just way to easy because you can safely ignore patrol paths and just walk up and around the NPC to backstab. There should be a 100% detection cone in front of the npc with a radius of 60 to 80 degrees.
- Light needs to be taken into account more, much more. You shouldn't be able to ninja your way around crowded, well lit zones without putting in some effort, ever, no matter what your perks and level are. You should be required to use invisibility for such endeavours, and it should be limited in a way that makes sense within the game world. Otherwise its just a no-brainer.
In essence, NPC AI needs to become more natural because right now its ridiculously easy to exploit.