roxy,
I put 2 Nightlighters on my pool and am entering the 6th season. I have the high-wattage one, 50w -which has a high & low brightness setting, and the 35 watt. Both are great lights, and automatically turn off after 3 hours so you don't need to worry about them burning out. They really light up the pool. I have an 18x36 oval and have them on opposite diagonal corners. We use them many, many times during the summer often swimming well past dark when the kids are out of school. (Let's hope neither of the bulbs go this summer since I posted this, knock on wood!)
Installed them myself. Easy to mount, long cords (28') and low voltage from the transformer to the pool.
Either way, at about $80 for the 50W and $60 for the 35W, at 6 years it cost me $23/year to light my pool. Well worth it and I'd replace them with the same product again.
Good luck.