Horrific smell if you don't keep everything super clean. Stinkier than ducks. And ducks are stinky.
Stressed birds (i.e., pretty much any birds kept in standard brooder conditions) can get violent with each other, and cause a bloody mess.
Predators can wreak havoc
Constantly upgrading pens as you learn what they need from experience
Feed and water twice daily if you have a bunch of them
They won't raise their own babies so you need an incubator and brooders with heat
Extras can be difficult to get rid of if there's not a strong market for them.
Likewise, extra eggs
Eating them is definitely an option for keeping population in check, but you have to slaughter them yourself--it's too expensive to take them to someone, and most slaughterhouses won't do quail anyway
The males can be noisy
They can die for no apparent reason sometimes
Sickness can pass very quickly through the flock once it develops because they are in such close quarters
People will think you're weird
I don't think the meat tastes that great
Eggs are a disposal problem unless you eat them, and they are tiny (although having a good pair of quail egg cutters helps with this) (and they are delicious)
If you have a lot, egg collection daily will be time consuming
You won't make money--chicks sell for 50 cents each around here, and adults for $2 to $3. Some people give them away free. It costs more to raise them than you'll get by selling them.
Except the wild and golden strains, it's difficult to sex them until they start crowing
Does that help? I still love my quail. But I keep smaller numbers now in a very natural setting--a 10 X 10 aviary with grass and weeds and honeysuckle and lots of dirt and bugs. They are easier to maintain this way because they have fewer health problems, fewer stress problems (fighting, feather picking, etc.), and I only have to change feed and water about once a week because there are only seven of them. Also, their pen never needs cleaning because of the low population density--nature cycles everything through quite nicely. Oh, and the largest number of eggs I might have to collect in a day is six.
I am a huge proponent of keeping them in urban and suburban settings because they are smaller, less obtrusive, and quieter than chickens. And the eggs are delicious. But I am talking about small numbers--a dozen or so. In larger numbers, they are a bigger pain.
Good luck. I think you're very smart to ask for all the bad stuff, so you know what you're getting in to. If you still want to do it, then you're the right kind for it.