It was the biggest, most rapid change to me. I went from a robot to a mother in like a month. I used to have to think of my reactions to things that "required" emotion, now they just come out sappy. For example: a co worker said "the only B word a girl should be called is beautiful" around everybody at work. I remember a time I would've chuckled and said "that is the wussiest thing I've ever heard", but I seriously couldn't keep myself from thinking how sweet that was, and I just blurted out "AWW!"... and everyone looked at me like I was crazy lol! I've found myself crying over simple crap like being shown how to do stuff, truly caring for people going thru distress, and genuinely being happy for others who do things with great results (unless I'm jealous, then I get sad).
My sex drive is far more oriented towards how a guy has treated me lately, other than how a guy looks. Looks are still a factor, but treatment will turn me on as before the looks did it. Looks are more of a qualifier now rather than an aphrodisiac.
Mood swings.. wow, watch for those. I can go from getting up happy in the morning to on the verge of tears because somebody points out a stain on my shirt, then back to happy after seeing a kitten picture. I'm starting to control it a little better but it was bad for a while.
I think a bit less focused now too. I used to be able to concentrate on one goal, but now when I see what I need to do, I see a million different worries. My classmates joke that I over analyze stuff. I had some bit of a problem with this pre-HRT but not to this degree.
There have been some annoyances with the mental / emotional changes, but I wouldn't go back for the world. I love who I've become! I'm generally more happy than ever. However my estradiol levels are sky-high, so that may have something to do with all of that.
EDIT: Also, the way I've handled anger has changed. It's like the difference between blowing up a stick of dynamite and eating a cupcake. They actually have the same amount of energy, but pre HRT I'd blow up in an instance and be back to normal afterwards (like dynamite). With HRT I get mad and simmer all day long, like eating a cupcake. I miss being able to get mad and then just being like "SCREW THAT PERSON.. ahh better".