There are minor "glitches" with the 811 receiver, but Dish is working out the bugs. There are software problems with the 811, but they are updated via the phone connection. The only problem I've had with the 811 is switching from off air signal to Dish signal, the 811 will sometimes freeze. A reboot clears the problem. That hasn't happened in awhile, so maybe they fixed the problem.
As far as HD content, obviously there is not alot offered by Dish. They did add TNT a few months ago which is nice. I get to watch some of the NASCAR races in HD and 5.1. Pretty cool!
The main HD programming I am receiving is through off air antenna signals. Personally, I think the picture is better from the antenna vs. satellite, but since my TV is only HD ready, I need the 811 for off air. Good programming from off air. National football games, NASCAR, golf, baseball are some of the things I usually watch via off air. There are TV shows as well that are broadcast in HD, but I don't watch too much network TV programming, sans the aforementioned programs.
On the other hand, you wouldn't believe the amount of BS you will watch in HD just because of the picture quality. DiscoveryHD and PBS crap especially. ESPN HD is nice. Sunday night football games are broadcast in HD. Looks and sounds sweet.
I have not looked into Voom. I've heard of it, but that is about all. I chose Dish vs. DirectTV because of programming. I did a long comparison, I thought Dish would suit me better.
Hope this helps.