What was it like!? By Community standards, what's the biggest change you've seen from vanilla to now. Also how was the economy and the feeling of doing the raid for the first time. ? To name a few
What was it like? For its time it certainly felt more like a natural world then any MMO I had played to date. At the point when this game out the WoW quest system was a revolution, many games before it just had you grind mobs down over and over again to gain levels, making quests gave the world and its characters life and although the quests were generally basic they rewarded you with big boosts of exp and new gear so you always felt like you were growing your character as you played and they also helped to guide your character along a natural path for progression as you leveled.
The biggest change is the simplification of the game, the original game was fairly complicated compared to now. Every level past 10 you'd get a talent point and you'd have talent trees to be able to slightly upgrade your character every level. Now you get talents every 15 levels which certainly have bigger effects but theres a reason people miss the old talent trees, sure it was easy enough for people to post what the 'best' build was for each class and what not but that still didn't stop people from at least trying to do some interesting things. Not vanilla specifically but the old talent system brought out things like Shockadins, Fan of Kniving Rogues, Rogue tanks, ect. There was some crazy things you could do, many were unfortunately nerfed but a few of the ideas lived on.
It wasn't just talents though you used to have various resistance on gear and would need specific types of gear for raiding generally several sets among other things. World PVP was also pretty big with epic fights between Southshore and Tarren Mill in one of the first areas where horde and alliance shared a zone, fly points were the only good means of travel, You got your first mount at level 40 which only had a 60% speed increase but it felt like you could go anywhere with a 100% speed mount at 60 which as other said was crazy expensive. Now you can get a mount at level 20 for all players but theres also a Bind on Account mount you could get that lets you use a mount at level 1.
Speaking as a Rogue its one of the biggest that was changed in terms of class mechanics. We used to be able to disable traps, find locked boxes out in the open to pick and raise our personal lock-picking skill, then you had poisons which we had to craft instead of being an instant ability that they eventually came and then they just stopped using them for some of the specs in the current game. Rogues were also able to completely wreck people in 1v1 pvp with stunlocking which frustrated the hell out of players and really started a meme about people hating Rogues. Also class quests, you got a lot of abilities this way and depending on the class you at times had to travel all around the world to complete them.
Pretty much the entire game is dramatically different then it used to be, in both good and bad ways.
The one thing that people do seem to forget a lot of the time about vanilla though was that... the game was completely fucking broken almost all of the time. Server disconnects, lag, ect. were more constant then you might think, then you had various classes that had specs with abilities that didn't work as intended others had entire specs that just were not viable and you couldn't get a group because you weren't the right spec. Certain bosses didn't work properly or would glitch out and be damn well near impossible to kill, ect. The game had a LOT of issues looking back on it...
But it was still so damn amazing for its time. It felt rewarding to level and earning that first mount at 40 really felt like a right of passage. Each class really felt like it had its own identity Rogues had its own skills and professions that no one else had and each class had their own unique twist in that way. The game was much less grindy then many other MMO's of its era but at the same time it never felt easy, you'd need to group up to get many quests done in order to complete a zone and actually know how to play your character to complete even some of the earlier dungeons.
I think the best way to say it is that the game really did reward you for the time you put into it... but it still demanded a hell of a lot of that time.
Modern WoW is just to easy. You queue into groups and generally just run through the dungeon without ever really having to try, you queue for a raid and can auto attack and let everyone else do the work and generally not even be at risk of dying in most cases, ect. Legion had some good ideas and some great effort put behind it but the game evolving as it did ended up losing a lot of what made it so fun in the first place as they added all of these new quality of life changes. The group finder was a great and useful tool but it also caused a lot of problems because some people just flat out suck at playing their class or even understanding basic concepts (like don't stand in fire) and this caused people to endlessly complain about how 'difficult' dungeons were, which in turn made Blizzard cave and nerf dungeons to the point where now they provide no challenge even in a party that just hit max level. Then you have Raid finder which I like the idea behind (giving a chance for everyone to see raid content) but same kind of thing, if anything was even remotely difficult the playerbase would whine and complain until Blizzard nerfed it making it so you don't even need to remotely learn any mechanic to complete it which is just stupid and not at all what the raid experience is.