I got the Canon 50 f/1.2 (LTM) a few weeks ago. I decided to go with this lens instead of the Noctilux or the even more exotic Canon 50 f/.95 for several reasons.
The primary motivation to go after the Canon 50 f/1.2 instead of the other options is money. I think it cost me about $250. That's a not unreasonable sum for a ultra-fast lens. By contrast, the Noctilux is $3800, and the Canon f/.95 can total up to $1200-1500 including M mount conversion.
It's a fairly hefty lens. The focus throw is 180 degrees which is nice for accuracy. It has an infinity lock. The infinity lock initially annoyed the hell out of me. Now I am used to it, and it is really not a big deal.
How are the images? This is a 40 year old ultrafast lens. To expect it to perform on the order of the Noctilux would be unrealistic. It does do a damn nice job, though. It's kind of soft wide open, and improves rapidly when stopped down. I haven't done any side by side comparisons with it yet, but it seems to be a tad sharper than my Industar 61LD at equal apertures.
All in all, it's a good addition to the camera bag and the 1/2 stop over f/1.4 actually helps more than people might say.
