Standing on the brink of my transition, I can't answer the question, but I have thought a lot about what to expect. I do think that, for a time, life will seem boring and I'll feel a bit directionless. Right now, there is an exciting goal and a lot of changes, plans, things to do, etc. Other parts of life go on, but in what's looking like they'll be a back seat kind of way---the main focus is on this transition. Once it's done, you have to start another transition: back to living, not just changing your gender. It's common to feel empty or depressed for a bit after achieving a major long-term goal, and I don't think gender transition will be an exception to that.
I am trying to keep in mind that the transition itself is not my goal. My goal is to live my life happily, just as a woman. For me, that means trying to focus as little as I can on the technical aspects---the various steps. Those are a means to an end, not an end in themselves. For example, I expect I will want to have GRS eventually, but I am not trying to make up my mind at this point. It's a long way off, and when I get to the point that I currently expect it will make sense, I think it's distinctly possible that I'll be happy as I am and not feel the need. I'm trying to treat the whole process that way: each step needs to be done for a reason, not just because it's what I'm "supposed" to do. After all, that's the whole mindset I'm trying to escape!