I used firecore as well and worth it.
I find it is very useful to do, especially if:
You use a service like unblock us to make it seem you live in the US for certain protocols (not illegal)
The above allowed me to get NHL center ice, / MLB / us netflix etc (of course have to buy NHL center ice, etc)
I also enjoy a jail broken apple TV for a cheap streaming media server that I have working combined with some network drives of media content
.XMBC is a bit of a pain to setup with it though, had some issues, primarily due to the fact I was trying to stream via my mac book air with mountain lion OS X (they made some changes that are not sorted out yet since the OS version is still in development)
However, the firecore media player for the most part does an OK job with video files. They are lacking a playlist feature for music, but I use airplay for that for now.
Cheers