I think there's not just "the building process". Part of it is planning, which I love to do, part of it is building, which I enjoy if things go right (more detail below), and finish, which I usually don't bother to do.
I'm an engineering student and contrary to popular belief I like to put to practice what I learn. The problem is most of the theory we learn can't be applied to rockets, and a lot of trouble I have with my rockets can't be solved by what you learn at Uni. But there's always the experience of others that you can count on. So I spend a lot of time thinking up projects in their basic dimensions and simming a lot, and every now and then I decide to build a rocket, which means I have to get into detail on the planning.
I hate construction when I don't have an exact plan; since I don't have that much experience in construction I would have to spend a lot of time during the building process making up my mind on how to solve little problems -- another factor is that I try to do something new (electronics, MPR/HPR multi-stage etc.) on every rocket and improve on things I did wrong/badly on past projects (notably motor retention...). What I don't like about construction either is when I realize I lack the right tools to do something. Ok, making good ogive nosecones is something very tough, so it's usually outsourced, but making body tubes and CRs in custom dimensions from scratch should be doable. So I try to get my hands on tools, jigs and machines that allow me to do the job well.
A rocket to me is something technical which should work well in the first place (<- engineering ;-), good looks come second. So I usually don't bother finishing a rocket since I don't even get around to building much.
Oliver