1) You can only rent HD content. AFAIK, none is available for purchase.
2) You seem to have a very slow connection, because the only 3 hour dl I've had was for the HD rental of Hannibal. That was >6GB. Personally, I wait until a video is at 60% before I start watching it, and that goes for my PC as well. Perhaps this is an example of "the soft bigotry of lowered expectations", but I do the same with non-streamed video on the web. for a Buffy episode, this means waiting about 15 minutes after starting before I watch it. I usually use this time to queue up other vids, or check if my PSP needs an update (natch!). The only way I can think of for Sony to have any way of improving DL speeds is charging for the network, which won't happen. So, I compare this service to what my PC offers, and because it's on my TV, it's superior. What are DL speeds like on XBL, and is there a difference between a Live Gold DL and a vanilla Live DL? I didn't see any metrics other than an anecdotal "impression" that XBL vids are better in the consumption. I would like to hear more concrete comparisons.
3) I've seen industry folks complain about the firmware updates on both the PS3 and the PSP, and you've seen my comments.
Seriously, if you leave your console off for months, you are going to have to download an update. The complaints have always sounded a bit manufactured to me. I happen to prefer the frequent updates to the alternative: none at all. Can you perhaps give a comparative impression of the update process on the X360/Wii? The DS?
I'm not trying to invalidate your experience; I'm sure you're being accurate about your feelings and that your frustration is genuine. I'm just saying that, just like that relationship that never started, you do have to invest something to get anything out of a relationship. And, just like trying to catch up with an old but not-quite-familiar acquaintance can be uncomfortable or awkward at first, things get easier as you spend more time together and recognize the true benefits of what seemed detrimental at first. I'm sure the reverse experience could be had with someone who prefers their PS3 to the X360 if that person spent the majority of their time with the PS3.
My real criticism of the PS3s video download service is that the downloads seem to be one-time only. When you download games, they go on a list and you can re-download them to the same system an unlimited number of times. This is great if you have HD issues and need to reformat, or if you replace your HD without doing a backup first. Fortunately, I have confirmed that the PS3 backup feature saves your downloaded content. Unfortunately, that is the only current way to ensure you don't have to call support if anything happens to your HD.
I would ask that you try again, but don't wait 2-6 months before you do it. It was unpleasant this time, I hear you. the first time I used the service it was disappointing, so I'm empathetic to your first impression. Subsequent usage has changed my mind. It may do the same for you.