With the recording of AC3 audio via optical cable I had problems. The recording starts to falter. I have not pursued and take now basically via the analog connection of stereo sound on.
The HD picture quality is amazing. That's all there is to it. Playback of files with HD players like WD TV Mini Istar or HD without problems.
This is already my second unit, as I had the first return for a firmware update. The dealer said that according to Hauppauge no damage was observed. But the fact is that I exactly had happened, what already many users report on forums and indeed even at the current firmware update 1.5.6. After the update, the device is no longer recognized. It is the message "Unknown Device". The installation of the previous firmware is no longer possible and restoring an system backups also does not help. The attempt is to get up and running with other PCs again just as unsuccessful. The device is then over. I can therefore recommend only expressly to take firmware updates distance if you are satisfied with the device ("never touch a running system").
Another error that occurred with me, were wave motion in the picture, which could clearly be seen in the black area. This was due to a loop in the circuit. I had everything (PC, player, HD PVR) to connect to a power outlet and then the image was quiet. Not a failure of the device, but something to do with the building.
Despite this unfortunate circumstances, I can only come to the conclusion: Top HD recorder!
Update 12/06/2011: Have the unit for several years now in use and am still very happy. From a firmware update I have refrained until now. Sometime I have (HDMI-to-VGA / Component converter) hinzugekauft an HD Fury2. The two products are a great team.