I'm familiar with the l298 I have used it before with pic micro's to drive steppers, the thing I liked about the idea was being able to get a stepper to run from a single power source.
Surely if the motor gets the correct voltage and has 90 degree phases it will run up to its full load.
However starting as pointed out might be an issue, loading on the motor from a zero start might mess up the phase shift causing an allready loaded motor to have less that odeal 90 degree phase shift.