I am 54, and I have been on hormones nine months. Only one thing about MTF HRT is really for sure, and that is, the HRT is going to turn you into a woman. The only variable is how long it is going to take.
At nine months in, I am starting to have trouble passing for male. I put on my old male Levi's and a male T shirt to do the yard work today, and I looked in the mirror, and I looked like a girl wearing her boyfriend's clothes.
I'm not large in the breasts (38A) but I grew an amazing butt after only a few months on hormones. My face is a work in progress, but the hormones have already given me a body like a teenage girl -- 5'7" and size 10/11.
And like others have said, the psychological benefits are wonderful. I am far more serene and patient, and the low frustration threshold and temper I used to have have all but disappeared. Most important, I smile every time I see myself in the mirror, and sometimes I go look at myself in the mirror just so I can see myself and smile. Because, for the first time since childhood, I can actually see me!