For our tests we used a Samsung Series 6 46-inch (LA46C650) LCD TV playing a wide range of files and formats. From DivX, WMV, H.264, MKV and DVD videos, to WMA, MP3, Real Audio music files, and many formats of picture files.
We had no issues playing high quality MKV and DivX movies at 1080p. The picture quality was amazing with no signs of stuttering. Unlike the Western Digital TV HD that downscales 1080p content, the picture quality produced by the Box Office was comparable to that of our HTPC. Also, when fast-forwarding or rewinding through movies we never lost audio sync, something many media players that we've used tend to struggle with.
We noticed that most of our audio/video files from movies and TV shows only had audio when using the LCPM option, and not RAW, which supports 5.1/7.1 channel audio. Being a budget media player this might not be a huge issue for the Box Office, and the fact that you can switch between the two is useful.
When playing high quality Blu-ray ISOs through the 10/100 network we had no stuttering issues whatsoever. Although Gigabit networking would have been better, the Box Office didn't suffer using the wired connection. That said, as mentioned earlier the networking abilities of the Box Office are not as solid as they should be. In fact, after our initial testing we are now having trouble getting this function to work properly all the time. There are a number of workarounds posted online but after trying everything, it seems a firmware update is in order to make this go away completely.
Using the USB wireless adapter (802.11g) wasn't as good for playing back high-definition content for obvious reasons. The limited bandwidth caused occasional lag spikes and stuttery playback with Blu-ray movies, while also making copying data from a networked computer to the Box Office very slow. For the smoothest operation possible we suggest you forget about wireless operation and stick to 10/100 wired networking.