There are plenty of scientific studies out there (both industry and academic) that demonstrate creatine's effectiveness for a variety of sports. Creatine if taken properly with a proper diet volumizes cells and provides a compound that the body normally requires for muscle maintenance, growth, and energy (remember the ATP electron cascade from high school bio?...I don't either), but just in major doses. The advantages from creatine is a noticeable increase in muscle volume, power/endurance, and recovery (and this will lead to bigger muscles). You will lose some water volume when you stop taking it.
I started taking it again after my backsurgery when I returned to the gym. Within a couple of weeks I noticed a marked increase in how many reps I could do and most importantly to climbing, an increased ability to push out a couple more. In the gym this translated in getting that great pump. I find that I also have a little more explosive power. I think this is the area in which there are conflicting studies. Too much muscle can certainly be a hinderance, and I agree that the best training for climbing is climbing, but strength training and maintaining/adding more fast muscle fibers (lifting, jumping, sprinting) and slow (endurance) can only pay off in the future.