I have just spent a week or so playing with some steppers. A comment I would make is that generally they run smoothly when they are run properly. but are noisier at low speed than at higher speed.
For a while I had the connections from the driver to the motor incorrectly wired and it would not run at all at high speeds or run with energetic thumping noises very slow speeds (< 5 steps/sec) and the motor really felt like it was not happy.
Also if you run half step mode it will be quieter than full step which is in turn quieter than wave step patterns.
They only rotate as fast as you send pulses. There is an upper limit after which the motor rotation can't keep up with the pulses and 'locks up'.