I am not still playing 4e, but I'll chime in nonetheless.
I think there are two main issues you'll have. The first is that many 4e players relied on the digital tools to the point where they didn't bother buying the physical books. With the demise (AFAIK) of all the tools, this means that many 4e players don't have the game anymore, or at least not more than the core books or whatever. If this isn't the case for you, this won't be a problem.
The second issue is the overwhelming number of choices to be made vis-a-vis powers, paragon paths, epic destinies, and feats, especially as characters level up, and the lack of digital tools makes it very difficult to sort these easily. The powers for, for instance, a fighter, are spread out across multiple books (and that's without even addressing mixing in the stuff from the Essentials books). I remember leveling up being more of a chore in 4e than in any other edition of the game, even 3e.
The other thing I'll point out is a reminder- 4e combats are very, very slow. They tend to drag unless you tweak the system in some way or ways. The math is so tight that you can predict that an encounter of the group's level is pretty much going to take three rounds, but those rounds will take forever to play through.
All that said, if you can overcome those issues, I think 4e is a great system for what it is good at, and I think it's gotten very short shrift from the D&D community at large. Monster design, skill challenges, epic destinies, traps and hazards- there is sooo much good stuff that I wish had made it into 5e.