BRUHHHHHHHHHHHHUnless my memory is failing in my old age, WotLK added XP Emilinator NPC's and much of the REALLY good shit is from long Quest chains in PvE.
Head / leg Libram enchants, spellthread / leg armor, shoulder enchants will become red. The enchant will still show but it won't give any stats. Spidersilk boots and drape is req 19 instead of 20+. Lucky Fishing boots get req level. Hunters get aspect of the cheetah, shamans ghostwolf and druids travel form. Healing power turns into Spellpower. I've prolly missed a ton but I guess those are the big changes.