I've taken up playing my hunter again. He's level 27 now and very close to level 28. I am playing him with the express purpose of being a great damn hunter when I reach level 80. Right now, I'm training myself in the use of Frost Trap and Distracting Shot. So far, I've been doing very well with soloing quests that I might not have been able to had I not decided to train myself in the use of these abilities. Some experiences that I have had.
The new LFG tool works well even at low levels. It used to be impossible to find a group for a low level dungeon. Now it's easy. Even if you can't get into a dungeon, it requires minimal effort, so you won't waste your time. Just queue up and continue questing while you wait for a group. This brings us to...
I got into a pug for Blackfathom Deeps just by queuing in the Dungeon Finder. The healer never joined us in the group. Instead preferring to quest in Redridge Mountains, possible going to jump into our group at the last minute to grab the extra loot. The tank AFK'd and didn't rejoin us in LFG so we couldn't get a new healer. So a DPS warrior was in a prot spec and tanked for myself and a warlock through 3/4 of the instance. At which point we were able to vote kick the AFK tank (there is a limit to how often you can vote to kick), take bake control of the group, and invite a healer to finish the instance. Between my bear offtanking and the actual tank, we did incredibly well throughout the instance.
The new quest tracking features make questing require much less effort than before. It allows you to see all of the quest objectives that you have in the zone so you can effectively plan your path around the zone to complete them. No more will you get back to town and hit yourself for forgetting about a quest.
Heirloom items are still going strong. At some point, Blizzard introduced an heirloom chest that also offers an XP boost (10%). I just need to get my hunter a bow, and non-pvp heirloom shoulders and he'll be decked out for quite some time.
Basic mounts are now trained at level 20, for 4g. Epic mounts are trained at level 40 for 50g. Flying mounts are first trained at level 60 for 250g, and epic flying mounts are trained at 70 for 5000g. Cold weather flying is now available at level 68 if you have a level 80 character to buy the Tome to learn it.
All of this has made leveling alts much easier and faster. Does leveling need to be hard? I don't think so. Leveling should be about learning your class' mechanics and learning the lore of the world, not spent running around zones that you have trouble in, dying to creatures that aggro you.