I think the powerclean is a movement that you'll never get perfect...you'll get better at it the more you practice, but you could do it for the rest of your life and never get it perfect...kind of like an asymptotic line!
Its a great movement for generating power and teaching your nervous how to generate lotsa power, but like other olympic lifts can cause injuries if you don't do em properly.
I generally think the powerclean for upto 3 reps is a great warm up movement to get your nervous system fired up prior to your workout, but unless you're doing it for a sports specific training, its not required for training to just look good.