This lens lives on my 600D. The only issues I have with it is it's not compatible with full frame. It is my walkaround lens of choice, but then the only non-prime I have any time for is my 70-200mm L
The 30mm f/1.4 is xtremely sharp, superb build quality and it survived a fall from 1.5 metres onto a gravel path with just a few scuff marks (though I wouldn't recommend testing its dropability for obvious reasons) and did i mention how well f/14 performs in low light conditions?
Having heard all the stories about focus issues for x% of copies, I brought one of those focus testing things you can print off with me when I bought it, and asked to see the exact copy I was purchasing on my camera at point of sale at Yodobashi Camera in Akiba.
No problems.