For me, it's been a whole bunch of different things. Various sorts of memory problems, issues with processing information and solving problems and concentrating, at times very challenged if not unable to put into words what's going on internally whether thought or emotion, fatigue (yet sometimes also problems with being able to fall asleep, despite being exhausted), quick temper at times, problems keeping emotions in check in general, personality changes, some crazy dreams, "dual" dizziness (sometimes I feel I'm dizzy, other times I feel the room is dizzy, sometimes both), a floating feeling like I'm not always fully in touch with reality, confusion, having to concentrate to put together sentences and keep a thought going when I talk, fighting at times to not slur my speech, sensitivity to light and certain noises (usually people noise like talking, etc), a slight claustrophobia/panicky feeling around lots of people as well as just with being indoors sometimes, switching back and forth between not caring about the cold much and my normal intolerance for cold (suspect I've also had a few hot flashes, crazy as it sounds), muscle tension (especially in my neck), pressure in my head, weird headaches (migraines?) that I seem to feel emotionally more than physically (usually I notice the "sense" of a headache for quite some time before I become aware I'm physically in pain), having "brain resets" where I forget what I'm doing and where I am for a split second (did this one time in the middle of trying to sign my name and had to really think for a moment to remember how the letters went), will sometimes try to do or say one thing but something else comes out, intolerance for stress (prolonged or overly intense stress makes me want to throw up), loss of appetite (don't always eat much even when I finally can force myself to), heightened sense of smell concerning certain things...

(eek, that list is longer than I realized)

Probably some more things in there, I don't ever seem to be able to remember it all in one sitting (did I mention memory issues?)