Over the last few months I've had a number of hardware problems with my MythTV server. The machine itself locked up fairly regularly, and there's been big problems with the driver for the dual-tuner card that had previously worked flawlessly. I finally got the shits with it and bought a hardware PVR on Saturday, the Beyonwiz DP-Lite.
I've held off buying an off-the-shelf PVR because they've tended to be pretty poor. The UI of the Beyonwiz is quite primitive, and very very confusing in parts, but it's good enough. I wouldn't recommend it for my parents though.
You'll note I didn't buy my employer's PVR product. It has one significant limitation for me: while it has two tuners, only one can be used to schedule recordings. The other is reserved for live TV viewing, which to me is a huge lack of insight into the way you use a PVR. Hopefully that will get fixed in one of the coming software updates. It certainly has a vastly better UI than the Beyonwiz and the movies service is quite attractive.
There's a few things I miss from MythTV beyond the UI. The browser scheduling interface is a lot more flexible than IceTV + Beyonwiz. With MythTV you can ask it to record a single episode of a programme each week, which means it can shuffle the recording to a repeat in a non-peak time if there's a conflict for a tuner. This device doesn't do that at all. I also miss the automatic ad skipping, but that's less of an issue because we only really watch ABC and SBS.