Rented it myself this past weekend, super sharp, great bokeh, but I don't think I need it. My take is if you are considering two of the following 24L, 35L, or 50L and don't necessarily need the extra stops of light or need the flexibility of a zoom then this is the lens for you. In that context it's not terribly overpriced...in every other it probably is.
Love mine... Except it has a decentered element in it... Right side much softer than left. I sent to Canon and they basically told me they can't fix it. So it is going back and I will be getting an exchange.