The 468 x 60 commonly stinks as an advertising placement. The text is smaller than many other modern units, whichmakes it a problem for this placement to face out on a online page with modern ads. From a design attitude, you do not have enough real estate to truly run both text and an image, so the picture isoften placed as a micro image to the left or right of the text headline on the banner. Compare that to the typical300 x 250 design, which uses an honest sized image and slaps a call to action in 24+ pt text around the top of it. I customarily wish to squint to see what the 468×60 banner is even speaking about.
Older sites may performwell with this format and it is certainly worth testing. The one saving grace is that this unit can fit ina diversity of locations that will’t accept a leaderboard or Medium Rectangle. I do use a few of those units because of this.