I bought a 2nd hand 28-105 F3.5-4.5 lens in excellent condition very recently. I took it out for a test run today. It is indeed a great walkaround lens for full frame DSLR, just like a swiss army knife of a lens. It even has a 1:2 macro mode that is very versatile. I did not feel it has any real flaws, other than that I wish it could go a little wider, and perhaps be a constant F2.8 but that is asking too much for such a budget lens! Sharpness and focussing accuracy was quite impressive in real world situations, colours are nice and neutral and this lens has very little distortion that I can detect for a standard zoom lens. The location I went today was at Bollywood Veggies around Lim Chu Kang area.