Best of all the WOW titles, best END game I've ever played to date, heroics and raids were outstanding challenge/reward.
Difficulty: It was perfect. It was hard enough where you had to gear properly and play properly to get through any heroic or raid. There were great guild-breaking raids that really made you feel a sense of TEAM and accomplishment if you could kill that end boss. My guild raided only 3 nights per week and we could still accomplish all with a mature, properly trained and geared group. WOW had the difficulty level PERFECT.
Fun Factor: All my free time seemed to be devoted to Burning Crusade because it was FUN. It was fun to clear the zones, to run the dungeons and to learn the heroics and raids. It was fun to train my pets on my hunter (gone now) and to learn the right combination/releases on my paladin and to try and stay alive, and still do top damage, on rogue. The introduction of alliance shammy was just in time. Enjoyed the new races. The raid bosses, themselves, were fun.. Lady Vashj and Kael were the best and Archimonde a swift pain in the butt, but when you got them-- what a sense of accomplishment!
End Game: Without exception, the best in PVE, of any MMORPG I've ever played.
PVP: Didn't do much of it and nothing stood out as great.
Leveling: Enjoyable. Minimal grind. Great new zones.
Crafting: Still a bit of a grind, as always, but not nearly as frustrating as it became later on. My armor sets went a long way and allowed me to get through the early raids with ease. Later on, making armor seemed a complete waste of time as it was garbage and was out geared in a couple of weeks, or one raid, whichever came first.
Story: WOW is never big on story and I can't even remember why the gate was there or what it was all about. Didn't ruin the game not to have a story. Other games are much better on story WOW is about the battles, not so much about story.
Community: Best community I have ever played with an MMORPG. It was difficult to find groups and you were remembered by your personality and skills and invited back if played well. The LFG system broke the wonderful community as far as I am concerned. I made life long friends from having to find like-minded, good/mature players.
Artwork and Music: I loved the music. It is rarely mentioned but I often flew around exploring just to listen to it without interruption. The artwork is average yet adds amazing charm to the WOW titles. Some of the newer games take themselves way too seriously in this department. These are games, and WOW graphics always have a fun and familiar flavor I enjoy.
Combat: This title had it perfect, and without all the graphics bells and whistles. If you wanted to solo while leveling certain areas you really had to know what you were doing and yet it gave you enough skills to master pretty much anything on the map at level. By far, more than any other MMORPG, the classes were DIFFERENT. While some classes felt shut out of things because of it, I never experienced this issue. I ran heroics and raids with people who were able to identify the strengths of any/every class and could work around not having this or that class in the run/raid. It is part of what made WOW BC great and when they removed that it truly broke the skill level of guilds, players, tanks and, most especially, raid "leaders."
Overall, my best MMORPG experience to date.