What would i need it for? I use Lightroom, Aperture, Photoshop/Bridge . . . .
Are there any advantages using XnView?
I think you have already many tools to browse folders for pictures and edit them.
I prefer XnView as browser than Bridge, XnView has also capabilities to batch some basic editing. I find Lightroom interesting for working on some folder like holidays souvenirs but too heavy to browse many folders having rendered panoramas and their sources.
The best tools are the one the user know well and practice regularly.
Canon EOS 40D, EF-S 10-22, EF 24-105 LIS, EF 70-200 LIS - Canon G9 (wide-converter)
DxO v7.5, Autopano Pro 2.6, PS CS5 and time