Gan’arg: The mechanical masters of the Burning Legion, these engineers are the minds behind the devastating machines that help enact the will of Sargeras. To the demon hunters who find themselves staring one down in their binding ritual, perhaps they have an affinity with technology and a general understanding for the Legion’s war machines. Regardless, the Gan’arg represent very little threat to the demon hunter trying to control themselves.
One of my favorite features is the Smart Injection System, which automatically determines the optimal place for your character to get started with the guides, based on your level and quest history. In other words, it doesn’t matter what level you are currently, you can jump right in and continue seamlessly with the guides. It also means that you don’t have to be a slave to the guides, they work perfectly even if you’re also leveling in instances, battlegrounds, using heirlooms or rested EXP. If your level ever gets ahead of the guide, just use the built-in feature to skip to the right place again. Very cool.
Only really to expand on Gráinne's comment as regards the 'collecting' and 'roster development' sections - which are, as said 'distinct' although they are intrinsically linked - I would like to point you in the direction of the in-game Achievements > Battle Pets > Collect tab. There are a series of achievements called Raiding With Leashes, pretty much all of which can be completed via the auction house - if you have the gold/inclination - or by completing old raids.
The main topic for Classic at the moment would be whether the game is actually harder or just has more redundant activities you have to do before doing the stuff that's really fun. This is actually a good discussion to have, and not just for WoW, but gaming in general. The main sticking point for now, as most people are on (relatively) low levels is the breaks between killing mobs, especially for mana users. In the beginning it's actually refreshing having to think about what you can and can't pull, not just running into a bunch of mobs and killing them in *insert current optimal time to kill Blizzard determined is the most fun*. The food/drink breaks after a few (or even one) mobs provide time to actually look around the scenery and the mobs you're facing, and while there isn't much strategy involved at these levels, you still at least pretend to plan out how you're going to get to that quest mob without being killed by the 4 random ones surrounding them. Not being able to pull whatever mob you want, and actually having to check what mobs are there when you don't have interrupts yet (casters tend to be a nightmare) is definitely more difficult in a real way than what we have today. As a caster, having to actually think about which spells to use based on mana cost (and perhaps even using lower ranked ones) is definitely more difficult and requires more engagement with your character than we have in modern WoW.