The bathroom, to me, is the perfect testing ground for those who are scared to make bold decor decisions. It's a small room (which makes any project you might tackle in there a bit more affordable) and it's not a place where you spend a whole lot of time. So if you, say, make a huge mistake thinking that, yes, fuzzy wallpaper was definitely the way to go... you can at least live with it for a while. It won't be staring you down with it's wrongness in exactly the way a misstep in the living room would.
That said, I think painted ceilings are definitely a "do." In every room, really. But definitely start with the bathroom. Because, yes, you can fix it cheaply or live with it for longer. But also because you'll probably really, really like it. Like, a lot.
In a room where most things–tile, furniture, fixtures–are designed to blandly not offend, it's nice to exercise a bit of boldness from the top down.