I love sequels. I love getting to take those characters out on another hair-brained adventure. It's the nature of us as humans to crave very strongly the "Same but Different" feel that a really good sequel is supposed to give you. I love sequels.
Right up until the moment I'm the one writing it.
With sequels, part of the problem is that we've been training to write the first book in a series, not the last book or the middle book. One thing we have going for us is that there are some really amazing sequels out there:
The Empire Strikes Back
and, umm, you know, that other sequel...
Okay, I'm gonna level with you, there are very few sequels that make me happy that I'm dealing with a sequel. There's something about sequels that make me tremble in fear. Largely, the biggest fear is that people lose their ability to tell stories. For instance, the reboot of StarTrek: the absolute pinnacle of the movie (for tension purposes) happens 15 minutes before the end, and then Spock goes and punches out Khan. *sigh* And this is a common problem in sequels. The actual beats are misinterpreted by the very people in charge of making the sequel. And I live in fear that I'm also making those mistakes.
Of course, the real problem with writing a sequel is This Song!
(That's what we do in Hollywood)
(And everybody knows that the sequel isn't quite as good...)