This seems like a fair, independent review.
Review: Wi-Fire
All this really is is an external wireless adapter with a larger, directional antenna than whats embedded in your laptop. Which is not a bad thing. But it seems large and clunky and every review I've looked at said it didnt clip onto the laptop very well.
At $79, I'd look at other usb and pcmcia wireless options including wireless-n adapters. Not a whole lot of hotspots and open access points are using wireless-n at this point, but that'll change over the next few years.
Another option is simply a wireless cardbus card with a better chipset than what came in your laptop. A lot of the broadcom and other el cheapo integrated wireless cards arent that good. A card based on something like the Intel 3945 would be a good upgrade.
You may also be able to upgrade the internal minicard in the laptop. These are usually under a little door on the bottom of the machine. For Dell's, a lot of the cheapos include the 1390 or 1490 chip set. Okay but not as good as the 3945 and you can get an upgrade from Dell. Its not as easy as plugging in a USB device, but its about the same difficulty as changing memory in a laptop. Open a door, push a tab aside and take out the old card, reverse the process to install the new.
You're not going to get a 2-3x improvement in range or throughput with a new internal/cardbus card, more like 30%. But that may be all you'd get with an external USB device like the wifire...