I'm a fairly recent user of Topaz Photo AI, the most "automatic" of their products. I've been using it mostly to up-res and de-noise some older digital images and scans. It's fun and usually works quite well. If I spent a lot of time tweaking I might match the results manually. But in many cases these are images where I'd be unlikely to spend that much time.
As others have said, you do have to watch for artifacts, usually where it tries to guess at faint texture or pattern. I find it helps if I turn down the sharpening sliders a little below the defaults and then add conventional sharpening using Lightroom. Face recovery tends to overdo it a bit, so I usually reduce those settings also.
I've been impressed by the built-in optical corrections from RAW files. I've run it on some pics without any other enhancements just for that.
The pace of updates is really impressive, at least with Photo AI. Seems like there's a release with tweaks and fixes waiting almost every time I fire it up.