The fact that Cookie's Tenderizer from the Deadmines had +3 instead of +2 strength. The fact that the Stormwind south bank had one instead of two mailboxes. The fact that Jaina's Proudmore's name was "Jaina Proudmore" instead of "Jaina Proudless." Stuff like this isn't what mattered. It was arbitrary. If Cookie had dropped a shield instead of a mace and Jaina had been named Susan, nobody would have cared. It wasn't specific details like these that caused us to enjoy the game.
Related to this, we’ve seen a lot of questions about the general invite process and want to clarify a few things. The method in which people are invited from the opt-in pool is not on a first-come-first-served basis, but instead we look at a variety of factors such as the age of the account. That said, the amount of closed beta invites that we’re sending out is rapidly decreasing as we have met our current population needs for testing. We’ll regularly reevaluate the need for additional invites as we go through the testing process.
2. Achieving. There are many pet battling achievements in game, and following the natural trail through the Taming [Continent] achievements up to Pandaria, and then on to the Spirit Tamers, Beasts of Fable and the Celestial Tournament was an epic journey for me and for many others. It's well worth doing. The Celestial Tournament is still, IMO, the pinnacle of PvE pet battling. However, WoD and Legion and BfA have added more battling achievements.