Wheellock muskets were FAR better than the flintlock muskets that replaced it.
The reason they were replaced: $$$
A wheellock uses a spring windup mechanism to sorta work the opposite of a flintlock. Instead of flint, the jaw holds pyrite. Instead of like a flintlock where you get (hopefully) a single spark when it is struck against the steel, the wheellock does the reverse.
The rock does not move like the flint. It rests on the serrated wheel about 3" in diameter. You wind up the wheel with the special key... when you pull the trigger, the wheel spins.
Now... unlike a flintlock, the wheellock makes a HUGE ball of fire/sparks -- just like a fargin grinding wheel. It will work in the rain. It fires far more reliably than a flintlock.
But. Relative cost? One wheellock would usually cost about the same amount as 30-40 flintlocks to produce. They were for royalty, not sojers.
The one I am holding on the book cover was my 11-times grampa's in 1637. I got to hold it when the Rijksmuseum folks dressed me up in 17th century A-dam militia clobber. Weird, weird, wonderful feeling. It still gets me pulse-pounding to think of it. You can see 7 pre-measured wooden powder measures draped across my magnificent chest. Behind my right hand on my hip -- that holds sooperfine powder for the pan.
The boorango weighed about 25 pounds. You had to have an oarlock-lookin' thingy to hold it up and steady. It shot about a 1/4-pound punkin ball. Just about exactly the size of a ping-pong ball. (3/4")