I played for a while in 2013. I don't recall the exact dates, but I think it was a period of several months. It was before the game had any purchasable content apart from the game itself, though there were various other things in the item mall that you wouldn't call content packs akin to the expansions available today.
What's remarkable today is not how much the game has changed, but how little. Most of the things that I've encountered are not so much "oh, that's new" as "oh, that's still the way it was". Maybe it's "oh, that's different from other games I've played more recently", but it's still the same as it was in 2013. That's not how it goes for most MMORPGs that release expansions.
And that's not a bad thing. It means that the game didn't try to reinvent itself and discard its original playerbase in pursuit of some other. As if such a transformation ever works well. Some people who played Star Wars Galaxies are still sore about what that game got changed into.
I use a controller, and for a while, the game felt more awkward than I recalled. Then I tinkered with settings for a while, and found the "action camera", which probably didn't exist in 2013, and that made controller play a lot more comfortable.
Back in 2013, I played at a resolution of 1280x1024. Now I play at 4320x2560. The game does scale the UI, but it doesn't scale it very much. Lots of things are very small at 4320x2560. I find it peculiar that they offer four sizes of scaling the UI, but the smallest isn't very different from the largest. If they have the capability to scale the UI, then why not actually scale to resolutions higher than about 2560x1440?
The game's wonky physics is as annoying as ever. There are trade-offs between fancy graphics and being able to make the physics match the graphics. Guild Wars 2 goes heavily for the former. A recent look at WoW made it obvious why I hadn't noticed physics problems there: the polygons that the ground consists of are enormous, so that the game can get the physics right.
To be fair, GW2 likely isn't worse than a lot of other games in this regard. The problem is that unlike most other games that are kind of sloppy with the physics, GW2 made it matter. Some vistas are a pain to get to, and some jumping puzzles are just awful. You have to know where you can fall through the ground or stand in mid-air, and whether you can jump from this spot to that one or if the height difference is just too much. And the way to find out is to try it--and perhaps fall to an instant death if it turns out that you can't. Sloppy physics is fine for some genres, but definitely not for a platformer.
The game world is still populated, and if anything, the outdoor zones seem more populated than before. If you've got enough players to fill one instance of a zone, then you can make it look populated just by scaling the number of instances up or down as needed. GW2 is now more aggressive about closing old instances than it used to be, even warning you that they want to close your instance. It didn't used to do that.
Renown hearts are still a nifty mechanic. They're much better than the old questing approach of run to an NPC to pick up a quest, then run to where you do the quest and do it, and then run back to the NPC. Instead, you just run from one area to the next and do whatever it is that there is to do in each area. ArenaNet has also done a good job of making the tasks varied.
Another underrated part of the renown hearts is that they usually offer multiple things that will get you progress. If one option is poorly tuned to make progress way too slow, or even completely broken and uncompletable, then you can just ignore it and do another. For the completionist, that's a huge improvement over being stuck at 99% completion because the other 1% is bugged. And there will be bugs, because welcome to computer programming.
Upon returning, the game wanted me to find out about Scarlet's War. It really didn't have a good transition into the post-Zhaitan storyline. You've rallied to slay Zhaitan and save the world, and then we're going to tell you about this huge war that happened after that but is already over so that you can't experience it. Except that while it was going on, it was breaking various parts of the world that interfered with you heading out to kill Zhaitan in the first place. But it's still some epic event that everyone in the world believes happened. It's kind of like what it might be like to be comatose for several years and then awaken to learn what happened while you were sleeping. And it doesn't make for good storytelling.
And then you get shipped off to the Crystal Desert so that you can pick up a mount and unlock masteries to help you with the content on the way to slay Zhaitan for the first time. Apparently Balthazar is evil now and some unknown character is inside your head talking to you or something. And everyone expects you to just know this. Maybe it makes sense if you go through the story in order, except that they've now added game mechanics to discourage you from doing so. And also you can't, because season 1 got lost almost as quickly as it was created, but is still canon for whatever reason. Or maybe it wouldn't make sense in order, like how Eye of the North was so incoherent. I'll probably find out eventually.
The crafting system is still terrible. There used to be two useful professions: jeweler and chef. The others let you craft stuff only after you'd leveled so far past it that it was useless to you. Now there is only one, as with ascended jewelery readily available for laurels, we can strike jeweler off of that list. The others may eventually be useful to craft a legendary or something. But grind something stupid to 500 to craft the one thing that you care about is completely stupid. At least crafting doesn't actually wreck anything.