I am now seeing several posts coming up saying that some important things are broken from this patch... pip-boy, VATS, reloading, among others...
darn it guess I'm going to keep waiting...
Yes, I think you're right and backups are mandatory at this point...
M
it seems alot of these issues are fixed by asking steam to revalidate the archive, install newer drivers for gfx card (if you are ati at least the 10.10c drivers and what ever the newest nvidia ones are), reboot pc, restarting game as saves are corrupt. All sorts of small fixes like deleting the dx9 dll fix and then revalidating the install.
Short anwser from me is YES! install it. it fixed my performance issues with the game. I have a 5970 gfx card and a 6core amd cpu with 8gb ram.. so it's not my pc but the game.
Corrupted saves are fixed as well as optimizations for gfx and other stuff like fixing the npc bug.
I'd copy your steam apps/common/fallout nv directory to some where (other hdd or burn to dvd's for example) before you update because with steam it's a simple matter of deleteing the old files and just copying back the directory and playing the game again.