got the 30mm lens today and so far i am impressed.
the build quality is good. i did a quick focus test and did not see any front / back focus issues. the size of the lens was a pleasant surprise since i was expecting something bigger and instead it's fairly compact and fits well on my k7+grip. the focus ring has great feel too.
otherwise, it does not have HSM or an AF/MF switch on the lens but that's just fine with me since it seems that screw drive lenses have less problems.
overall i am very impressed. the only
complaint i have is that the sigma focus ring is
backwards (i think it conforms to canon style). not that it's a big deal
can't wait to take it for a test drive and see how it performs wide open!