I use media server regularly. My workstation, which is up in a loft, is my main MC location but I also have MC installed on a laptop downstairs that I hook into my A/V set-up. Then, via Media Center, I can stream whatever I want to hear. This is all done via wireless. I've been able to stream video this way too.
The reason why I prefer to do this rather than network mapping is I have access to all my playlists, all of the songs are already imported, sorted, and rated. I don't have to maintain two separate libraries. If I know where something is on my workstation, I can get to it without a problem on my laptop.
The only thing I wish Media Server had the ability to do was to allow me (as a designated "admin user") to make changes to my database remotely. I have other people who access my Media Server and they should be read-only.
Other than that, I've had very little problem with Media Server and it's one of the features I use to sell MC to my friends.