I returned my first example because focus was erratic, frequently miles off, sometimes smack on. One hour it would be good, then awful later. Awful at inifinity (always missed) usually perfect up close, did not like white subjects etc I thought I was losing my mind. the new one has come thru and it performs perfectly on my 5D II and I look forward to using it on my 1n and Eos 3s for some good old film work!
I have to say after my as yet unsolved 85mm issue (where my 85 L II is amazing on my 5D II and Eos 1n HS, but will not focus at all accurately on any of my three Eos 3 bodies (which all focus my 135 and 70mm lenses perfectly) I was thinking about ditching Canon when this 24mm came through all wonky. I am pleased to say the replacement lens focuses very accurately at all distances and under all lighting and its a darned good performer. At f1.4 it is a bit soft or glowy, but still quite good really. By f2 its very sharp and by 2.8 blinding. Its a very nice lens indeed and is miles better than my 24-60 zoom (which is no slouch at f4 and beyond).
If you get one of these 24 L IIs be sure to put it through its paces focus wise and send it right back if it throws you too many curve balls (and you too think you have lost your mind and must be responsible). This is a lens I am going to enjoy using a heck of a lot alongside the 85 1.2L II. now they just need to update the 35 1.4 L II!