I stupidly kept my bike in a locked shed and of course it was stolen. I'm thinking about hanging my next one from the ceiling, but may consider a pulley system over just a hook. And some sort of stopper to protect the wall. Show me your pics/links!
I have the 2-Bike Gravity Rack that REI sold a few years ago (I think we've had it for 8 or so years now). It is great, doesn't require a ton of hardware to keep it balanced on the wall, takes up minimal space and gets the job done. It functions fine, if you're only holding one bike - I highly recommend.
I agree with @StatenIslander. I have used the ceiling hooks before and have definetly had a mountain bike fall from the ceiling since I missed the center of stud. I use the racks that lean against the walls to hold my bikes. They don't take up a lot of space and can store multiple bikes stacked.
If you have the space, we use the Rubbermaid FastTrack system. It's sturdy and affordable (we have 7 bikes on our 84" length though 6 is probably a better fit); will require patching the wall though if you're a renter.