If you already have the Maglite and you really like it, maybe the MagLED upgrade is worth it.
However, there are other readily available complete lights for cheaper that are brighter. Two I can think of off the top of my head are the Husky 4 Watt LED light (uses 2 D cells, black body with silver head, looks like a lightsaber, can find it at Home Depot) and the Task Force 3 Watt LED light (2 C cells, silver body with black rubber grip, says 60X on the package, can buy from Lowes). Both lights are significantly brighter than the MagLED module, and are designed around the LED.
Then if you want to get into higher-end lights, shoot, there are tons! If you read around on the forum you'll see there are many many good lights, some affordable, some more expensive, whatever you are looking for. Almost any of the higher-end Cree or SSC P4 lights and even many of the cheap junk ones, will be brighter than the MagLED.
The MagLED has its charms though. I think personal preference is important here, if you love your Maglite then this is an easy drop-in way to make it run an LED.
Also, like another posted mentioned, the MagLED module has great runtime. You don't always need a super bright scorcher of a light, in some ways it might be better to just have a light that doesn't eat batteries and is reliable and there when you need it! I think the MagLED fits this bill, as do many well-built lights.
If you really want to have some fun, do what I did, I had a MagLED module that I took apart, removed the stock LED emitter from, and installed an SSC P4 emitter into. This made the light WAY brighter and it has worked out awesome!
If you are interested in that, you would have to buy the MagLED module and an SSC P4 emitter, and then use some thermal epoxy to affix the P4 onto the MagLED, being careful not to let the base of the P4 make electrical contact with the MagLED module case. I think there is a thread on here detailing how to do it.