I'm pretty new to triathlon, coming to it from running, so my bike is mediocre, and my swim is pathetic. I needed a way to to improve my swimming, and saw the Guppy Challenge posts. I'm only competitive if there is a competition, so it seemed like a good way to get me to the pool as often as possible.
I wound up doing 46 workouts in the ten weeks, more than 70,000m. I followed the program fairly closely for the first seven weeks, and then spent the last weeks working on the problems that were revealed by the video my wife shot.
My speed increased dramatically- I think I took more than 15 sec/100m off my time (starting at "very slow" has some advantages. My low hanging fruit could be tripped over). My endurance increased as well. I'm only scheduled for sprint and olympic distances this year, so I'm in a much better position for this season.
It took a while, but I can now do something that resembles dolphin kick. The superman back kick drill still causes problems, mostly due to a crowded pool, and my flip turns are almost not there at all.
I've continued to swim regularly, and now have a good assortment of drills to keep me busy.