Plex does not support external UPnP servers (like from my NAS) but rather gives you (yet another) server. All media content has to be present on local or mounted disks.
At least this is my observation after a quick test install..??

This might not be a problem for some users, for me its a show stopper.

I just spent the afternoon trying the latest version. Initially I was enthused enough to start wrestling with it... and to get it to access all of your materials correctly, expect to do some work.

It's regular expression access to identifying files is rather limited. I was able to improve on that a bit by hacking it. That I had to do so was a minus. And it's lost access to NetFlix and other online entertainment even though it claims the plugins are live and running. More people at the support forums are facing this issue and response from developers has been nil so far.

In the area of file hierarchy, there was no way I was going to start messing with my iTunes file system because it couldn't recognize there was more than one album in more than one subdirectory... like most people (and iTunes) organize their files. Same problem existed in its native acess as well as the alternative iTunes plugin (though the plugin did a tiny bit better).

It one MAJOR upside is that the interface is navigable from first launch, unlike such as Boxee, XMBC, etc. But that's not enough. And as time has passed, looking back and Plex's history and changes, it has had a long struggle trying to keep up. In part, there's some development paradigm problems that are holding it back, and some of those should be evident by comments herein.

I'll keep watching it, for it does "have promise", but it seems to have been in that same state for a long while now.

Release notes are HERE:

http://elan.plexapp.com/2011/10/31/state-of-the-release-2/

What the heck is this? No help, no manual, no nothing ... Is this a joke?

Amazing how many people just don't get it. Plex is not a way to "import your iTunes library" (don't understand that comment) or create a "smart playlist" (another I *really* don't understand in the context of Plex).

Plex is a home theater PC program, similar to Boxee and XBMC - and so much more. Like those it allows you to browse and watch your television shows and movies nicely organized, and access a lot of internet content from one seamless interface.

Plex leaves those behind in that it is a client-server system. You set up one library of your media - then it streams that to everything you have - your TV, your Roku, your iPhone, your Android, your iPad - all seamlessly.

The library is the key to it all - when you add media to the library it scans and matches it with metadata online, then automatically tags and organizes it so you can browse a TV show by season and episode name, or movies by director and genre. All with gorgeous cover art. No manual tagging for all of this to happen!

Compare what your music looked like ten years ago versus what a modern song bought from iTunes looks like - one has perfect metadata with artist, album, track, covers, even lyrics, and one is just a blob of music data. That's what Plex does automatically for your TV/Movie content - it turns those plain video files into fully matched, metadata-spiffy versions that you can then do all kinds of awesome stuff with.

It's not a "view iTunes content" program - if you want iTunes content and don't want to deal with the DRM entailed, buy an Apple product - which now means an AppleTV since Apple killed off Front Row.

It's not a "throw a folder of junk at it and it's on your TV" thing - it's much more organized than that. You *can* do that, but if your goal is simply "get files on the TV without metadata and organization", you'll probably be better served elsewhere. Such a Boxee, with it's extraordinarily limited local file support.

Does anyone have a clue as to why Plex always automatically changes the Audio MIDI from 2ch-24 bit to 2ch-16 bit whenever you open the program? I have not been able to find a fix for this anywhere.

Still no fix for crash-on-quit behavior? This has been happening since the very first time I installed Plex, many versions ago. I've deleted the preferences and started fresh, but nothing helps. I have literally never seen this program exit cleanly. It has crashed 100% of the time when I've tried to quit, from day one. This was on a brand new MacBook Pro bought less than two months ago, and this behavior was happening within the first two days I had the new machine, before I had even installed or used much of anything else on it.

Bottom line: Plex is just not very well made software. I really wish it would work reliably, as it's a nice idea and clearly better than what Front Row has devolved into, but so far it just hasn't been worth the trouble.

It's got a nice gui, etc, but the one feature I wanted from it (upnp client) seems not to work with my mediatomb server. I know the server works, because I already use it with my PS3, but on the Mac I seem to get nothing. CPU goes NUTS, and I get some audio, but nothing else.

Most disappointing. When will a decent upnp client for Mac appear??