The only positive comment that I can make regarding the Delkin pop-up is that it offsets the control buttons located next to the screen on the XT (Canon 350D) camera so my silly thumb doesn't accidently switch drive modes when I am shooting.
Tripping the shutter and finding that I am in self-timer mode is more annoying than having to open the darn pop-up everytime I want to check my image.
However, after switching to the 30D and 40D cameras; I have no problems accidently tripping the drive control button and thustly do not need the pop-up which is a great PITA for me.