I bought Luminar AI yesterday -- not so much for the sky-changing feature but for the "erase" feature, which I had on Luminar 3 and really loved until that program went blooie after I installed and began using Big Sur. Not a huge surprise since the program was older and not a huge loss since I primarily use DXO for my processing/editing anyway. I did like that "erase" tool, though..... I didn't bother with Luminar 4 since I knew that Luminar AI was on the way and figured it would be kind of handy for things from time to time. So I experimented a little with it after purchasing and downloading, and it'll be fine for occasional quick-and-dirty editing if I just want to mess around with one image quickly and am not processing/editing an entire folder's worth. It'll also be interesting just for experimenting, but in general I am not a big fan of manipulating one's images to the extent of replacing actual real skies with something else from a software program. For me, whatever the sky is in the image I'm shooting, that's the sky that will remain. However, I have been known to convert to B&W and make an otherwise boring blank grey sky grainy so that it looks more interesting.
Someone on Nikon Cafe also bought the program and he played around with the Sky feature and discovered that there are about 20 different objects that one can add to a boring sky -- along with the inevitable rainbow, hot air balloon, sun rays and such, there's a space shuttle (!) and, believe it or not, a giraffe. That's right, one can float a GIRAFFE in the sky!!!! Seems to me that they also should have a pig with wings, too..... LOL!!!!!
I think that Luminar AI will appeal to novices, the Instagram and FB set who just want to quickly edit and share their selfies and such, those who have bought a "real" camera and aren't quite sure what to do with editing images. It's pretty quick and straightforward when opening the program to see what one wants to do: there are the various presets and one can simply click on one of them and get pretty decent results. If a preset is a bit too much, there are sliders to control that. If someone wants to do more, actually manually edit an image, that is also possible, and again fairly straightforward when opening the editing panel.
I haven't shot anything today and have been busy with other things so haven't experimented further with Luminar AI..... Next time I do shoot something I'll probably play with it again. It's more of a novelty than a serious program as far as I'm concerned....