I'm liking the easy way the Environment Preview and Background HDRI settings work. Not yet sure how to rotate the background itself, but the results so far are quick, easy and produce good results. The Post FX bloom effect is nice, if somewhat tricky to control (as of the first attempts, that is). I've mainly tested it with HDRI backgrounds, and expect it'll probably work a bit better with in-scene lights.

Quite a few Cycles nodes seem to be missing still, which is unfortunate as it makes creating new Materials off of Blender examples harder (I know some people find it easier to work around these, but it'd be simpler if that wasn't necessary). On a positive note though, it's good to see a (limited, but still) set of Superfly materials included. A good step that'll hopefully be expanded upon. Maybe even contact the creators to include some of the commercially available sets.

Haven't made any attempt to compare render times, but OptiX worked flawlessly and quick so that's a good start. It had been a bit unreliable with some combinations of Poser 12 and Nvidia's drivers, but so far it seems fine.