I owned the 1.8. bought the 1.2 during the bing cash back, b/c I got a good deal on it, never intending to keep it. Ended up selling the 1.8, and keeping the 1.2. there are times that I miss the 1.8. It is a fantastic, fast focusing, small and light lens, with very good image quality. the 1.2 however has exceptional color, and images at f 1.2-2 are truly amazing. Is it 1500 better? not sure. Depends on what else is in your bag and how else you can spend your money.
Here is a shot in candle light, hand held, ISO 3200, f 1.2, 1/100 sec on 5d2. Possible with a 1.8 lens. sure. but I am glad I had the 1.2.
|IMAGE IS A REDIRECT OR MISSING!|
HTTP response: NOT FOUND | MIME changed to 'image/gif' | Redirected to error image by FLICKR
aside from that of course is the fantastic bokeh.