First off it streams off the net fairly well, I have better luck with my PS3 than my XBox 360. On the XBox I have to start a stream 2 or 3 times for it to finally catch, but after it has caught it works pretty good. It very well could be my ISP rather than PlayOn here but I really don't have this problem with the PS3. The software is just kicking off the ground, so I am sure it will just get better over time.
But what really put it at the top of my list is the following. A couple days ago I contacted PlayOn's API Developer support because I was interested in using their API and writing a file aggregator where it would allow me to do what Mediatomb is currently doing, feed video from my Ubuntu box. Since C# and DotNet is what I use at work, it looked like it was going to be a snap. They sent me to a site http://www.playonplugins.com which is a bunch of like minded media geeks with C# skills, and after a few posts there, it seems one of the moderators named "human" whipped out a fileshare plugin that was perfect using OPML so essentially it could handle multiple file paths or shares. This saved me a few hours of work and let me get back to killing things in COD4. ;-) On the page that you downoad the plugin I put instructions for making it work on a UNC share so I could have it read from my Ubuntu box over the network, so you can go check that out.
Now PlayOn with that plugin does everything! They also have a few other plugins you can grab from the site above that are very interesting. For the adults it has a plugin for you, which I won't go into depth here you can go there and check out for yourself. ;-) There is also an OPML aggregator plugin that you can just drop an OPML feed in a directory and it will stream that content. People are sharing OPML files and feeds through the site as well, even has it's own section of the board for that. There is one for the Food Network, HGTV, The Onion and a handful of others that really makes this PlayOn amazing for pulling together all your online video feeds as well as now your own local file share.
I think in a few more days my trial runs out, but this will be the software I purchase as I want to support their development efforts. I like the idea of something so easy and extendable, and the only issue I have is now I need to upgrade my Ubuntu box with more powerful CPU's so I can run this software on a VirtualBox XP machine instead of my main gaming rig. ;-)