Bright AF! I’m comparing this light “bulb” to a standard CFL, which I am replacing. My single CFL is rated at 13W, 800 lumens versus 82W, 9000 lumens. There is a BIG difference when comparing the two light bulbs. Then there is lag time when you flip the switch until the light actually turns on. It’s minimal. I estimate about 1 to 1.5 seconds. YMMV. I took off a star because it was a little weird when installing this light bulb, the time it actually turned on compared to a regular CFL light bulb, and cost. Because the shape is much different than a regular light bulb, I couldn’t turn it normally. It’s not really a bulb, but a collection of tiny LEDs in an array layout. I had to be careful because I was installing them very high off the floor. I estimated about 9 -10 ft off the ground. I didn’t want to break due to complacency. These things cost roughly $30 each, or $60 per pair. CFL are much cheaper per unit compared to these LED “bulbs”. I bought the CFL bulbs for around $12 for a set of 4. Lastly the lag is noticeable. When I upgraded from an incandescent light bulb to CFL, there was lag. At first it was noticeable. Because I’m doing a major upgrade from CFL to LED, there is expected to be lag as well. Overall, these things are great! They are brighter compared to a single CFL (800 lumen vs 9000 lumens). That resolves my need for a shop light. But the cost and lag time prevents it from being 5 stars. In due time the designers will fix the lag issue.