Wireless n hasn't been officially ratified within the industry, but it has, through years of tentative release, just about become set in stone.
If ever there were a time to upgrade, it's now. That said, it's worth pointing out that you might not even need a specific USB stick to take advantage of Wireless n's increased connection speeds: if you've got an Intel Mac, every model except for the 1.83GHz 17-inch iMac is natively compatible, although you'll need to pay Apple a couple of pounds to unlock the functionality.
Users of older Macs will benefit most, though; buying this device gives your Mac compatibility with just about every wireless router in the world, and drivers are included for Panther onwards, meaning you won't miss out if you don't have the latest edition of OS X.
Refreshingly, Newer Technology seems to have really taken the Mac to heart. The manual in the box gives comprehensive Mac instructions, though note that you'll have to dig around your system a little to get everything set up correctly. Much of this complexity can be blamed on the fact that this isn't directly AirPortcompatible, necessitating a separate wireless utility which you'll need to use to manage your connections.
Sadly, this isn't particularly friendly: at different times we had trouble getting OS X to recognise that the USB stick was plugged in, the custom software doesn't seem to save your network password, and aesthetically it doesn't fit in too well, not even using Aqua buttons.
That said, once the connection was up and running it proved fast and reliable, so the upgrade might be worth a little extra clunkiness. AirPort compatibility isn't all it's cracked up to be anyway, so there's little love lost.
As it is, this is a great solution for increasing speed and range, although don't expect to get much more out of your internet connection; even wireless g runs faster than the majority of UK ISPs.