There is a review at Military Morons covering the Vicker's magazine release and slide stop. I've recently put both of these products on my Glock 17 and 26, and find them to be an excellent. Glock should really put both of these on their guns in the factory; they're indispensable. I like my Glocks to have commonality of parts so that they feel the same, so all modifications are done the same for both.
I have large hands, and even I can't reach the stock Glock magazine release without changing my grip. The Vicker's mag release is just long enough that I can dump the mag without changing my grip, but not long enough to inadvertently drop the mag if the gun is placed on its side on a flat surface. Installation is about as easy as changing a memory card in a camera.
On stock Glock pistols, there is what they call a "slide stop", as Glock firmly recommends using the overhand method to charge the gun with a cartridge from a freshly inserted magazine. The slide stop can be used to release the slide, but it's very hard to do, especially under stress. Glock also has an aftermarket extended slide release that you can add to the gun, and it works very well -- too well for folks like myself who are used to a "high thumbs" grip from shooting 1911s. This grip can cause either one of the thumbs to be in contact with the slide release, which often results in the slide not locking back when the magazine runs out; and for me, it also causes the slide release to ride against the slide, inducing malfunctions. The remedy is the Vicker's slide release modeled after the Smith & Wesson M&P slide release.
Installation of this part takes a whopping minute or so with the use of a punch to press out a pin. Piece of cake. It's very unobtrusive, and yet is very easy to get to when you're dropping a locked slide on a fresh round. I'm a big fan. Both of these parts combined cost less then $30 dollars, and I highly recommend them.