We love the light from this Fluorescent Spiral Light Bulb. As with all of these energy efficient bulbs you need to wait a small amount of time for the true level of light to be achieved and that is the case here with each of the three levels of light. You do not need to wait for each level and can easily just switch to the highest level immediately and then it comes up to the brightest for that level in just a quick amount of time. I'm so used to this Fluorescent Spiral Light Bulb now that I barely notice the warm up period but I definitely enjoy the brightness (just exactly as bright, or a little brighter, than our old 50/100/150 bulbs) and I will be enjoying the benefits of a lower electricity bill for years to come. Highly recommend! We are back now to buy a couple more so all the three way lamps in the house will be energy efficient.

P.S., as far as the size of the Fluorescent Spiral Light Bulb, yes, these energy efficient bulbs are all slightly larger than normal bulbs. However, I have not replaced any lamp harps and have had not trouble fitting the bulbs into our lamps.