The biggest thing that kills immersion for me is pausing the game midfight to drink 5 potions or eat 100 apples.
I actually love the fact that the game pauses when you go drink and eat, it put's a tiny "turn based-ish" element into the game, where you wonder if you should consume meals, food or potions.
You can look at all your scrolls and powers, and think of the best way to escape/fight so you don't have to reset the game...
Planning during combat is a great rpg element in my opinion.
I frapsed the outcome of my latest sticky situation (where I lost my companion, all food and potions and fled into a foresty situation, where I came across a hostile mage.)
I was just finished buying 2 (yay) pieces of meat from a hunter when I saw the mage standing in front of a cave or entrance into a mountain. I easily fled further away from the road into a (small?) forest.
I waited a little and decided I should travel back on the road to Whiterun but suddenly the mage came out of nowhere into my flank.
I ran and got a little stuck on a small ridge, since you cannot jump on certain angles.
But only one attack in my back so far, and the second one didn't come, luckily.
I continued to run and I saw a guy sitting near a tent.
My suspicion of random encounters was raised so I stopped and tried to run in a small circle around him (couldn't go back obviously).
"I see you burn"... "Never should have come here"
Two taunts in my back... I was ready to die, in a last desperate attempt to help myself I equipped healing in both hands, since I had no stamina left to flee with...
Lucky for me, there was nothing when I looked behind!
After watching the vid I realized the guy sitting near his tent actually attacked the mage, So instead of 1+1=2 it was 1-1=0
I will never know the outcome of that battle though...

http://www.youtube.com/watch?v=XKMqOrFRpMQ&hd=1