Fortuitously, I was exhausted and fell asleep at 1 this morning, which meant I woke up at 9, which meant I had to doze around for a few hours lest my upcoming 3 nightshifts fry my ass. So I got UP at noon, right when FedEx came with my iPad Mini. How's that for luck? He said, "You're just now getting UP?" I said, "It's an early day for me." That confused him enough he didn't say anything else. Anyway, I had the afternoon to play with it unexpectedly, including reading my RSS feeds on it. People are appalled by the screen, apparently. It doesn't look as nice as my big iPad 3 screen, but to me it looks the same as the Paperwhite I just returned and is comparable to the original Fire. I have to admit the Galaxy Tab had a prettier screen. I read quite a bit on it, and it didn't make me want to rip my eyes out, as others have claimed. It's actually quite nice to hold. As pretty as the large iPads are, they have always made my wrists hurt when I hold them for any amount of time. First-world problem, but one that this device solves beautifully.
If I really want to do tricky photo stuff, I don't think it'll be such a good device for that, but for LOOKING at photos, it's fine. I "suffered" through the pre-retina iPhones just fine, after all. The one graphical issue that is just ugly is the iPhone apps stretched up to the iPad screen---notably Instapaper and Tumblr for me. They look OK on the iPad 3 and horrendous on the Mini. It's not the graphics themselves, either, because if I use the Tumblr interface on the Web or look at Instapaper via FlipBoard, they look fine. But yeesh.
As for the jittery, slow performance complaints, I didn't notice any of that. I don't play the super-duper graphics-intensive games, but I do like driving games, and it not only handles them fine but is easier to maneuver because of its size.
I haven't had enough time to decide whether it can replace my big iPad. I may decide to keep both, or I may give one away. My dad never gets to use his household's "communal" one! Meanwhile, in the few hours I've had it, I've felt a decided preference for it for this-and-that stuff, and when I go out I'll be tossing it in my bag instead of the big one. Travel and such may be a different story. Hard to tell after just an afternoon.
I think the bottom line is going to be that it depends what people are looking for. I was looking for something to read comfortably and voluminously on that synced other stuff with my existing devices---basically a 7-inch Galaxy Tab that did what my iPad did. And here it is. So I'm pleased. I suppose I'd be more pleased with a retina screen, but I guess my eyes are less discerning that other people's. It just doesn't look that bad to me. I'll trade lightness and battery life for it. When they figure out how to retin-ize it without those compromises, I'll trade up.