Is it really smooth rotary motion? There's a "dwell" at each end of the linear motion while reversal occurs and it seems that would translate into a "dwell" in the rotary motion. Is an un-pictured flywheel required to smooth out the motion?

Also, is there advantage to this mechanism over the common connecting rod driving a disk on the shaft? (or a jackshaft with bevel gears if the rotary shaft must be aligned with the piston motion).

Looks like a solution in search of a problem.