Yes, there are plenty of parts of the process which are pretty straight-forward - the conversion of the book to Kindle, for example - but there are other parts which will take days off your life, chew them up and spit them out. I genuinely have had no time to do any actual writing (excluding blogging, of course) for weeks.
It will settle down, over time, I'm sure. What it does, though, is appreciate the amount of work that goes on behind the scenes in the publishing industry. Of course, the people doing this day in day out have had a little more practice than me, and so won't get bogged down with some of the unexpected tasks. Then again, they are probably working on more than one book at any given time, so it all balances out.
It doesn't mean I'm not enjoying it, though. I like a challenge - it's pretty much what my day job is about, dealing with the unexpected - so it's not a problem.
But, like everything else, it's wise to go in with your eyes open, and expect that there will be some hard work (but then it probably wouldn't be as satisfying if it were easy, right?)