Mike,
I was thankful we didn't have to install a sprinkler system, but otherwise the requirements were very easy to implement. Most of it used scraps for blocking and whatnot anyway, so there was virtually no cost involved. In the overall house building process, the few requirements for fire safety were simple, and it's nice to know it's done properly.
Complying with seismic and ventilation requirements was a bigger hassle than the fire safety issues, though in retrospect, even those were fairly simple to implement. And again, I'm glad it's built that way now...
Anthony