anyone else find installing a bathroom fan harder than it looks?

Swapping an old fan for one that fits the same hole: fine, an hour or two. Putting one in where there wasn't one: yeah, that's where it gets annoying. The bits that catch people out are getting the duct all the way outside (through the roof or a wall cap, not just dumped into the attic, that's how you get mould up there), using insulated duct so it doesn't drip condensation back down, and sizing it. Roughly 1 CFM per square foot for a normal bathroom. Cutting the ceiling hole is the easy part, just check where the joists are first.