I recently went back to it after a break of 2 years and they've plastered SO MUCH content all over it.
They've also changed a lot of the progression mechanics.
The best thing about it is there's no real gear grind. You buy your exotics when you're 80 (which are very very affordable and you can do 99% of the content) and then if you like grinding it out for that 2-3% increase in stats, you can do that. But you don't have to do that in order to feel competitive.
If you like PvP, sPvP is very fun or WvW for organized mass zerging.
Fractals for high-end PvE and then there's like I think 15+ World Bosses, champion runs, dungeons (story & speed runs), Silverwastes, world completion, jumping puzzles etc
Personal favourites: Evolved worm world boss, Silverwastes (a whole map of events that eventually lead to having to kill 5 champions and then three bosses+ a chest train+a labyrinth+a huge jumping puzzle all on the same map) and guild missions (I can't stress how fun this is working or racing against your guildies every week)
The expansion is coming out in the next months as well and they're keeping to their mantra of horizontal progression. So you won't need to grind away for new gear to do the new content like other games. Instead you gain masteries which change how your class works.
I don't think I've played another mmo with so much varied well crafted content as a whole.
It's also buy to play which is the absolute best way to enjoy an mmo.