Already widely reported here are the strengths that I confirm: Piqué impeccable. AF K-5 quite effective even in low light (with firmware Version 1.16 Pentax K-5) Noise broadly weaker and discreet AF suggests that what forums even if the ultrasonic comments will do better. In contrast to models with Tamron or Sigma stabilizer you win well 200gr weight which is significant; next to the large mass of this type of lens. First photos indoors without flash hand lifted superb!