I did the TBC ones on a level 74 and later a 100, tanking and dps.. On the level 74 tanking was a mild challenge without optimised gear or max level talents, but we had a weak/slow healer too, no wipes. On the level 100 I was just chain pulling everything.. The Shattered Halls x2, Arcatraz, Magisters Terrace, Slave Pens to memory, mostly tanking.
Seemed easy as ever to me, dungeons at the start of WOD when we were in the pre-raid phase were considerably more difficult.