There's not a single feeling, and mostly it's pretty blah. I need more intense, interesting, or complex things to prick my ears up. I need something to challenge it to work harder to lift the experience above the banal. The outside world is usually pretty disappointing in this regard, which is why I often end up trying to generate those thoughts (and the consequent feelings) myself internally.
It does have the sense of an alternative commentary on events that's often in contrast to the external version, and this is the world that generates feelings. So as an example: someone might tell a not so great joke and internal commentary might say, "That's not funny. That's the 3rd unfunny joke he's made all night. He hasn't got a clue about basic humour", and I then react with amusement at the thought. Outwardly, it would seem like I'm amused at the joke, but really I'm amused at the filtered rendering of the joke; the interpretation of the joke. It's the reaction to the reaction. So the alternative commentary can offer up all sorts of feelings, albeit indirectly.
I'm not sure if that answers the question, or even if other IxFPs would agree with this.
EDIT: maybe I would say the most common feeling tone is "yearning".