While I can't say that I've been overly impressed with it, I have played enough in the past few months (as a new player) to get to level 120 or so, so there is at least enough content to keep you entertained for a while. The main issues I have with the game stem from the fact that it was always meant to be a driver for you to spend real-world money, and despite the fact that they have added a lot of content and NPC's to the game, it hasn't changed the base goal of the game - keep you playing and spending in perpetuity.
That being said, there is still a fair amount to do, and it will definitely fill that hunger for a fallout game, but you WILL get to a point where you notice how tacked-on and surface level all the content feels, and where you will have exhausted that content and are now expected to just grind out dailies and repeatable events to get better stuff and on and on and on...
If there was one single thing I would recommend that you do, it would be to figure out what type of character you want to play (shooter, power armour, etc.) and then research it a bit and use a S.P.E.C.I.A.L. planning tool, like
You must be registered to see links
. One of the shitty things about 76 are how the perk cards are metered out and distributed, and you will need to combine cards to make upgraded versions often. If you don't know what direction you are taking off the hop, you can end up gathering and upgrading the wrong cards to start with, and end up having to play many more additional levels to get the cards you didn't realize you needed in order to optimize your build.
I started playing Fallout 76 with the intention of going in blind and just discovering things as I went along, and had some fun doing so, but the one thing I wish I had known from the beginning was what type of build I was shooting for, so that I could strategically get the correct cards for it as I leveled up. Do that, and you won't end up spending 30-40 levels in build limbo while you acquire the back-catalogue of perk cards that you didn't realize that you needed.
Hope this helps!