I think if you're looking for the ability to stream live TV to your iPad in the house, I'd start with the free DIRECTV App for iPad. There are a lot of channels that will do live streaming. GenieGo probably won't do true live streaming, in other words streaming of live TV, probably not ever. But it does give you access to your playlist with just a few second delay.
Where this product really shines is as you said, downloading programs to it. I'll admit it takes a little planning since it takes about 105% of the program time to do it. In other words, a 60 minute program takes about 63 minutes to transcode and download. If you're planning a trip it will take all night (and then some) to get 15-18 hours of programming done.
However, you can set up auto-transcodes, which are like series links in a way, they pre-transcode particular shows when they come up on your DVR. That makes it a lot easier.
Once the content is on the iPad, it doesn't matter that you're using a scaled iPhone app, you get the maximum quality video that the thing can give you nonetheless. It really shines on planes and in hotel rooms where you would think that you'd get good wi-fi and you just don't.
I have both a GenieGo and a Slingbox, use both as needed, but I don't have an unlimited data plan so if I'm traveling the GenieGo gets the job done.