I picked up my 55LW5600 last night (it's born on date was March 11th so it was fresh off the plane) and can now clarify some questions I had earlier.
The apps available are at http://us.lgtvapp.com
3D YouTube channels play, but the set doesn't give you the option to switch on 3D, so you only see the videos side-by-side.
Comcast has 2 HD channels.. ESPN 3D and an events channels.. I saw some show about Mummys.
The web browser seems to be a full browser..speed was decent for light surfing, but I only tried a few sites.. I did try YouTube (from the browser.. not the app) and it required Flash 10 so you'll be limited by that.
NetFlix worked very well...better than on my Windows 7 Media Center.
The 3D 2 minutes previews on VUDU were nice.. I saw the previews for TRON, BOLT and Alice in Wonderland.
I'm surprised there's no Pandora.. it seems like all connected devices now have that one.
The above is all with a wireless connection.
Other than the above, I didn't really play with the set too much.. Most of the time was spent replacing the old set..hooking up the connections and reprogramming my MX-950.. Line of site remotes are so last decade
I went through the Picture Wizard setup and haven't done any more adjustments. So far I'm happy with the picture but haven't even watch a full show.
Feel free to ask anything else.