I own and use both lenses. Full disclosure; I also have the 85/1.2, 100/2.8L, and the 135/2. All of these focal lengths are represented by the (totally awesome) 70-200 2.8II zoom as well. This might mean that I am addicted to glass (guilty), or that I try to utilize the advantages that each lens has over the other (hopefully also true). Let's face it (I did when I gulped and clicked the purchase button for the 200/2) this lens is expensive and it is much bigger/heavier than the zoom. If you are needing to dismiss the zoom as inferior in order to justify the purchase you are really missing the point. This lens is not for everyone, but it is a killer lens! Some may say, hey I will just shoot at 200 ISO instead of 100. The problem is when you don't get to choose what the light level is. What about when the groom steps out of the center spot of the altar while you are shooting at 1/125, 2.8, 400 (from the mandatory balcony at the rear of the sanctuary) and walks to the side of the chancel, sits down at the piano which makes him effectively disappear (much like the predator). After my eyes adjusted to his black suit sitting at a black piano in a void of illumination I was changing my settings to 1/80, f2, and 12,800 ISO! I suppose that the zoom would have given me 25,600 but I was already horrified with going from 400 to 12,800. I could have used my 135 or 85, but that would put him much further away and he would have been in stark contrast to the comparative alien abduction that his bride and pastor were experiencing. Being able to Isolate him in the frame was critical. Getting the lowest ISO possible was also critical. From where I was, nothing in the Canon family was as well equipped to get the shot than the 200/2. Now I also got some great shots in the feature lighting of the altar at much more ideal settings. This also gave me a somewhat sharper image than the shots taken with the 70-200. I was also able to isolate the couple a little more at 2.0 than 2.8. But at least as important was the ability to shoot with the zoom in order to frame the bridesmaids and the groomsmen respectively. I do not view these lenses as competing, but as 2 separate tools to help a photographer get the shot. Any sports action shots when you are squeezing the shutter speed and ISO levels or just trying to isolate your subject will be incredibly well served with this lens. If you are a pro and need what this lens gives you, you probably already own it. If you are trying to justify it, rent it and you might just save yourself 6K and a backache. I use the zoom for more shots, but the 200/2 is a lens that will continue to perform for me when I need that reach and max speed. The zoom is a better value. An automobile is a better value than an airplane. I would bet that anyone that owns a plane also owns an automobile. The reverse is much less likely. This is a great example of a lens that for most shooters is better to rent than own, but one of the saddest days of your life just may be the day you return this one at the end of your rental agreement.