u will need a 24 mm f1.4 cos you might need to shoot at low light situations and you still want nice bokeh at wide angle..
distortion ? frankly.. i find distortion very well controlled.. cos prob I am very used to using wide angle ( 12mm ) .. so no issue.. I am usig a full frame by the way..
I use it for portraits, weddings etc.. it is one of my fav lenses.. basically.. u have to see wats yur shooting style to know y u need the lens...
its the same for all lenses..
some shots with the 24 mm wide open..
http://www.pbase.com/will03/image/83405893
http://www.pbase.com/will03/image/99796274
http://www.pbase.com/will03/image/97017799
http://www.pbase.com/will03/image/98946913