For the price charged now its discounted this is a brilliant lens! I got it for my G3 and its very sharp even fully open to f2.8, also despite the lack of a hood it deals with glare very well. My only issue with the lens is that I find it a little long to be a walk around lens, its great for 3/4 portraits, and general use, but its a little long for architecture full body situational and group portraits. Whilst I realise these aren't uses it was designed for, I used to used a 50mm for all those purposes on a film slr.
I'm still very happy with the lens though, and have now also got the 19mm, and between them they provide me with everything I need for walk around lenses. The 60mm equivalent focal length does have some advantages over a more typical portrait lens, I find it more versatile for real world situations, meaning you don't need as much space, and it can be used for other subjects more easily.
Edit: I'm still very happy with the 30mm sigma, but the 19mm will be replaced with one of the panny pancakes to make my walk around kit.