AQ20 is a really nice transmog farm. The worms called Silicate Feeder are actually the mobs with the best loot in the raids so be sure to loot them. They are found between the 3rd and 4th boss. Be sure not to kill ANY of the mobs in the room with the 2nd boss as that will start the encounter for the boss. You can go through the whole instance without killing any bosses, so you can choose to run the entire raid or exit after killing the worms by creating a group in the group finder and leaving it.
While not as powerful as it was before 7.3, this transmog spot is a good area to amass a large number of BOE greens that generally fly around the 35 – 42 area. It's popularity stemming from the amount of items that drop (and the potential value of those items) rather than the quality of each drop itself. Generally drops from these farms can take a while to sell even when using my TSM posting style. However if your low on transmog stock this can be an awesome area to hit every now and then.
40% of the book is maps with notes (useful always). 30% is detailed descriptions of the classes and their skills and spells and tips for playing them (useful when starting out). 10% is a list of items and monsters in the game (not very useful). 5% is an extension of the manual, telling you how to do things (useful). 5% is how to get started in each starting area (I haven't used this.). 5% is play tips (useful mainly to beginners). 1% is abreviations and what they mean (useful mostly to beginners). 4% is miscelaneous information.