I started out with the 35 1.4L on a rebel. Eventually I upgraded to the 5DmkII and I can say from experience its great on full frame or 1.6. Its a bit more versatile for full frame imo, though if you do a lot of head shots or candids (ie a bit further away to be unobtrusive) you will need to compliment it with something else obviously. Here is an example shot from when I had it on the rebel -