For the average user I would say that it would / will make no real noticeable difference in real world day to day use compared to a decent sata3 ssd. Not saying there is no difference, as there obviously is. Anyone considering one of these drives really needs to appreciate that there isn't going to be a life changing experience here! Though quite obviously depends on quite what your useage is going to be.
In my opinion and that's all it is... Buy one if you fancy having the latest tech and can justify the costs. Just don't expect a WOW moment like you would coming from a mechanical hard drive to your first ssd.
I've had one of the earlier sm951's and quite happy with it as my boot drive. Zero issues with it. But only bought one because it was a new build and I had spare cash in the pot. Run a more real word orientated test suite like PCmark (paid version to get the storage tests) and it looks seriously quicker than my Samsung 840 (runs best with the Samsung Nvme driver regardless of what Samsung say) but day to day.... If being totally honest, can't tell any difference. Though my system was pretty nippy before this anyway.
A lot of folks go on endlessly about boot times. But does anyone really care if your PC boots in 10 seconds rather than 20. I know I don't. There are far more important factors effecting boot times than the speed of your OS drive. Like... Which version of windows are you running. If windows 10, are you using hybrid shutdown / start up. Are you using fast boot. Is this a new install etc. Etc.
As to game loading times. Depends on whether (to a great extent) whether the loader is designed to take advantage of a very fast drive. Doubtful if many currently are. Pretty much backed up by comparison tests I've seen run in review articles.
Sorry to ramble. But you did ask ☺
No that was perfect, and basically lined up with what I thought/experienced, cheers!