Problem is this is a highly subjective question, only you can determine if it's worth it to you.
On paper NVMe is a colossal upgrade, over 2000MB reads compared to the 500MB of SATA3, however the reality is far less impressive. I got a 400GB NVMe drive when they first launched, and yes it is well over four times the transfer speed of my 480GB SATA3 Steam drive, and well over eight times the speed of my 480GB SATA2 Downloads/storage drive, however I only know that because it says so on the specs sheet and the benchmark apps.
As far as real world use goes, the SATA3-NVMe upgrade is far less noticeable than SATA2-SATA3 was, which in turn was less noticeable than HDD-SSD was.
Yes Windows does boot fractionally faster, yes games/applications do load faster but the difference over SATA3 isn't really that noticeable if at all in some cases. Depending on what you play it could even be worthless, I.E I can load into a World of Tanks or Heroes of the Storm match faster but that just means I get more of the countdown timer or have to spend longer waiting for other players to load lol.