I have this Raspberry Pi on which I had XBMC first. Hated it, still hate it.
Spend weeks on it to configure it but in the end it still messed up my library: didn't show DVD correctly etc.
I was always a happy user of Plex Mediacenter on my Synology, so I configured Rasplex. Working great ... can navigate through Plex but not play content. It says "playing" but does nothing at all.
Please don't convince me of XBMC, heard it is the best over and over again but I've spent to much time on it.
Plex works great, only the Iphone/Ipad apps don't.