.....this wont TOTALLY waterproof your boots. Leather will eventually wet out under constant immersion.
My suede La Sportivas have remained waterproof after using this nikwax. I havent tried them during HOURS of saturated walks yet, so thats why I`m only giving it 3 stars so far......
I also bought this stuf cos I didnt want my suede boots to dry out and crack during years of use.
La Sportiva recommends this and re-badges it as their own. Perwanger, the company which makes La sportivas suede, recommend this via email: "We also impregnate for example withNIKWAX only after several using (less is more)"
When you remove the cap from the bottle, youll find a crap sponge applicator which sits on top of the bottles mouth. It lets the fluid dribble off the boots and onto your pants.
Do yourself a favour and get some cotton wool (or any small square of absorbent fabric) and squeeze the fluid onto the cotton wool, then dab your boots with it. This method is far quicker and wastes less