That's so true. Many folks write in just to rant and rave about something. The vast majority of customers are happy and don't write. Forums like this tend to be skewed towards those who are unhappy. It's not a fair picture of what service is really like.
And yet, strangely so far only people claiming positive experiences with the product have posted.
Within similar products (DVR's, video cards, network routers) its quite easy to find products with very positive general reviews and very negative general reviews.
So I think its hard to say that one will only find generally positive or generally negative comments.
In fact, I'd go so far as to say that forums like this tend to draw primarily positive enthusiasts who are very willing to stamp out people with legitimate complaints.
As it stands right now, the consistent review scores from a large number of well respected review sites has the directv dvr ranked lowest, the dish dvr in the middle and the tivo dvr rated highest. The problem with those findings is that the tivo is the most mature, followed by the dish, followed by the directv box. So a lot of the negative reviews for the directv box and some of the negative reviews of the dish box may be related to older reviews when the products were relatively immature compared to the tivo product.
Does the directv dvr blow? Eh, not as much now as it did two years ago. But its still not as reliable as I'd like and the user interface response is often slow and erratic.
For the OP, since you're a prior dvr user, I suspect you'll find the directv box does some things better, some things worse, and other things differently. Some aspects will delight and others will annoy.
For myself coming from the tivo dvr, I found the limit of 50 series links, the lack of mrv, the inability to record a certain number of shows and have the dvr stop recording more episodes until I delete one and the remote control that requires you press a button and wait 2-3 seconds to see if it 'took' makes it a rather frustrating product.
In any case, I think that if you start from the premise that a highly complex piece of technology will give you no trouble at all and that its users never have any problems, you're going to be very disappointed.