I'm thinking of getting a WDTV and doing some researching.
@DAN20: the link you posted is not working for me. I get: "Sorry, but the page you requested does not exist."
As for Error Code 22, on WD's website I found this (sorry if this is redundant):
Which seems to indicate some issue between WDTV and Slingbox (engineers probably pointing fingers at each other).
At least to WD credit, they do post firmware release dates as well as firmware release notes:
I can't say the same for Slingbox. According to my Slingbox500, My box is on Rev 01.00.125. But I have no clue as to what was fixed or not fixed, let alone any "know issues" yet to be fixed posted anywhere, or when the current Rev got released.
As partners, one would thing that WD engineers and Slingbox engineers would all be on the same page. However, that looks like wishful thing. Apparently the communication line between WD and Slingbox is experiencing Error Code 22.
This issue was to do with an incompatability issue with the wdtv app and the new slingboxes (350 and 500), this was identified and the link i posted was sling acknowledging it and stating that they was working with wd to release a firmware update before the end of october.
The firmware update was released literally the end of the month but atleast it got the issue resolved. The version of the app seems more like the boxee version whereby there is a little 3secs delay before the stream is shown.
The app in the past was so glitchy and was hit and miss on whether it would connect, if you was lucky to get it connecting and streaming it would no doubt freeze and cause an increased buffer making commands go from 3secs to more like 20secs which was also unbarable.
The current version of the app is more stable and connects first time every time however, it's not stable on every quality setting, basic and good are usually stable without freezing, better will sometimes last for a little while but not even 15mins, best hd will freeze within a few mins. This is pretty much the same for all/most connected devices, commands are now 6 secs. People are trying to steer clear from the boxee as it's no longer going to be updated.
If you're planning on using a connected device on the same network then you shouldn't experience any issues, the issues are to do with viewing from a different location to the slingbox.
The alternative to a standard connected device would be hooking up a laptop to the tv, i was doing this for a while and used an android app to create myself a wifi remote, I've started using my wdtv 3rd gen again now it's a bit more stable but not liking the delay for commands.
The PC app will always be slings best version then the website player (watch) and then connected devices.
Check out the wdtv forums http://community.wdc.com/t5/WD-TV-Live-Streaming-Discussions/bd-p/streaming_discussions