Just "me too"ing this thread. I have a Hopper 1, no Sling or Joey.
Like the OP, I'm dismayed that the new UI has made almost everything not just a little bit slower, but WAY slower; it's teetering at the edge of being tolerable. There are very sluggish responses when when switching between the guide, the DVR, and live TV, as well as when making selections or just trying to view program info. Sometimes I have to wait 10 to 20 seconds for a button press to register.
In addition, I only get a black screen when I try to play my old DVR'd content which I had copied over to a secondary HD. It was working before the upgrade. Now I can only browse that HD but can't watch anything from it. There is an error message that pops up for a split-second when I start playing something, but I can't read it because the black screen is on top of it. I think it was something about checking the channel subscription.
As others reported, the fwd/back speed changes make it really hard to navigate as precisely as before. And the Home Media app is utterly useless now because it is only playing content in a tiny window in the upper right corner of the screen; the rest of the screen is black.
I would have thought that enough people would have complained by now that these bugs would have been fixed, but apparently there are no fixes forthcoming.
Upgrading to an H3 means paying a higher ransom just to get the same level of functionality (minus the fwd/back speed of the old UI) that I had before these UI changes crippled my H1, right? They already ding me $12 a month for the H1 DVR, $55 for the basic Dish America w/local channels...the total with fees comes out to $68.88 a month, which is all I can afford. For this I get no premium channels, half my DVR'd recordings are now unusable, I can't even use the Home Media app anymore, and it's ridiculously slow. I feel like a chump every time I pay the bill.