Summary: Depending on your criteria you will either love or hate this lens. First the negatives. This lens is soft at f/4 and improves little when closed. How soft is soft? Noticeably softer than the kit DAL 18-55 wide open even when resized to ~2MP (24" monitor).
Summary: I'm using this lens with my K200D. The lens is relatively compact, versatile, has high build quality, but performance is uneven. You never know if it will focus fast or hunt a lot, with no apparent reason. Focus at 70mm is not fantastic, as reported previoudsly.