Today I picked up an HD DVR, the Scientific Atlanta Explorer 8300HD (shown), from my local Time Warner Cable office. Here are my thoughts after setting it up and using it for 2 hours or so.
First, setup was easy since it basically replaced my previous HD set-top box -- same cables and everything. For outputs, I use component video (direct to TV) and digital coax audio (to the stereo). While I could have used the DVR's HDMI output to feed into the TV's DVI port, given the so-so picture quality, component video is about all it merits (but more on that later). As far as ports, the DVR also offers optical digital audio out, s-video out (?), and standard stereo audio out (via RCA jacks).
During the first couple of hours, the DVR reset/rebooted itself once, after which some really bizarre gobblety-gook appeared on the screen on some channels (see photo below). I hope this clears up soon. At least it's not on the channels I watch the most.
While the picture quality is better than standard, or even enhanced TV (you'd expect it to be since it's a hi-def box), it's noticeably worse than the Pioneer 3510HD STB (cable tuner) it replaced. Using the same cables and settings, compression artifacts are much more prevalent on most channels, especially those with marginal HD feeds. Watching ABC news tonight in HD, the border of the reporter's face against the dark background would literally shimmer as the compression algorithm tried to adjust to the moving, angled line. Not great, for sure.
Now, before I discuss the interface, I have to confess that I am a diehard TiVo junkie. TiVo is my gold standard that any other DVR will be compared against when it comes to the UI. With that said, the SA box is mediocre. It's not horrible, but some anthropological engineering of the user interface could offer some dramatic usability improvements. Plus, there are several features that I miss already (e.g., recording quality setting per show, auto-record by keyword, and the "boing"....where's the "boing?"). They may be in there, but I didn't find them in my brief usage tonight. And why is the remote (center) so darn big?
However, on the plus side, the 8300HD is chock-a-block full of good specs. It has dual tuners, meaning that you can record two programs at the same time while watching a different pre-recorded one. It sports a 160GB hard drive (20 hours of HD content or 90 hours of SD content), and, most surprisingly, an external SATA connector so you can hook up an external hard drive to expand your storage capacity without monkeying around in the DVR's guts...nice!
Anyway, I'm sure my opinion will evolve with time. Perhaps I'll even forgive the lack of a cute little mascot and forget about that big, friendly, yellow Pause button. Not likely, but maybe...
Update (2008-12-9): I've posted a step-by-step HOWTO: Expand the Recording Capacity of your Scientific Atlanta Explorer 8300HD DVR (it's easy...give it a try)