Rant/ I never got past 3.3.5a due to pirate servers not being really well made for Cata at release and afaik still today they are poorly developed.
I really dig the idea of seamless and stitch-less world map that Cata has introduced. But I also don't dig what WotLK was at the end of the expansion. I think TBC was the last epic time to play WoW. Maybe early WotLK. To me, dungeon finder and easy battlegrounds queue is what made the game less fun. Yeah, now you do not need to /yell in town square looking for some low level dweebs for them to join your party and travel to a far dungeon for half an hour. But that was the fun part, even tho it took time and effort. Mindless parties from queue killed fun. I remember in TBC looking for a party to go to Deadmines and it was an effort. Joining dungeon finder took me a second, but fun was not there.
My cousin began on private servers and then went to official during Cata I believe. Not sure, but I think he is still playing retail as of today. From his words, game became quite fast paced and you can level up really quick in a day. The whole game play was toned down to dungeons, raids and PVP. From outside sources I got the idea that it became like what happened to Diablo 3. Gameplay during story line was nice. But once first expansion dropped with endless rifts, game became - farm better gear in order to be able to farm even more better gear. Mindless farm simulator.
I am nostalgic for the times when players were friendly with each other. Moments like high levels coming to starter zones and giving out gold and gear to newbies. Contacting local chat or guild to find some payers that will help you with a quest. Asking for tips about certain quests. Actual team-play on battlegrounds. But the thing that will never come back is the sense of discovery. It only can be experienced once.
Even as of right now, playing AzerothCore singleplayer mode, I find best time was during leveling lvl1 to 40. Even alone, with bots. Nothing can beat that Elwyn Forest - Westfall - Redridge Mountain - Duskwood zone combo. I got this tearing up/shivers/inner peace feeling every time I hear Elwyn Forest theme. The Barrens are also speaking to me, but I was mostly an Alliance player.
/Rant