It is hard to judge how much dimmer it really is. The standard bulb throws out a very yellow light when compared to a good LED. Sure it is dimmer, but the color is truer to day light and most things are far easier to see in white (daylight) color, than yellow would be. I have this bulb and I can tell it all the light you need the in house. You can stand it on end and light the whole room with the light bounced of the ceiling. The spot goes a long ways, it's still tight and bright on my fence 60 feet from my door.
When it comes to usefulness, consider these facts.
A 3D maglite with that bulb will run for about a month continously.
The incandecent bulb in the mag wont even last long (rated at 36 hours), the batteries will be dead in a few hours.
The LED has no filament to break, filaments break very easy when they are hot. Turn on a flashlight and get it hot and drop it, you'll see what I mean.
With a LED, you can literally destroy the flashlight aorund the led and it wont break. The LED will last for ~10000 hours.