I've used both the latex and oil versions of Dry-lock (dry-loc?). They both work very well to prevent dampness from wicking through block and concret. If you have a serious water problem with a fair amount of pressure build up behind the wall, you'll need to apply Dry-lock to the inside and outside surfaces of the wall, which is pretty tough, given that the outside of the wall is likely buried. With a lot of water pressure behind a wall, it will bubble the Dry-lock off of the surface in areas that are prone to seepage.
The products are very labor intensive to apply. The stuff requires a LOT of mixing to get the solids to suspend in the liquid, and then the material is very thick and requires a fair amount of elbow grease to apply. You use a brush on the first coat, and can roll the second coat if you did a good job on the first coat. Essentially, your brush coat pushes the goo back into all of the crevases and pores in the concrete and the second coat fills pinholes.
My take on it is that as a retrofit, Dry-lock is a great product for helping fix a damp basement. If you have a wet basement, it'll probably help, but won't eliminate the problem.
KB