imho - MoP has some of the best raid designs. Definitely better than most TBC encoutners. Looking back at TBC encounters, those are some of the most boring fights. They were only fun because people were new to raiding.
The issues a lot of people are seeing is that they are getting bored of raiding. Overall, raids are the same basic holy trinity vs boss. Not much in raiding has really changed, and after doing it for 8+ years, it's not very exciting for a lot of people.
That's my subjective opinion anyway