Good thing they just brought out a hotfix,,, its easy to solo bosses now.
While I like the new changes (already leveled from 1 to 110 on a shaman), there are some glaring issues I noticed while leveling, especially in dungeons.
The biggest issue I have is the class balance is reeeeeeeeally skewed at a lower level. Certainly I don't expect w/i 1% DPS for non-max level classes, that'd be silly, but I was seeing things like WW monks doing 3-4 times the damage of other players who were playing well. The balance gets better as the level increases, but there could still be improvement. This extends beyond DPSers, as it applies to healers and tanks, too. While I'd see a bear tank struggling with a normal mob pack and things get really dicey if an extra mob gets pulled, I'd see a blood DK or prot warrior pulling multiple packs with huge absorbs to where the healers could just DPS unless a mortal strike effect hit the tanks. I could see healers spamming their fast/expensive heals and still not be able to keep up at damage. From specifically a shaman perspective, you actually put out more DPS as a resto shaman than elemental until you get mastery at 78 or the packs are huge so Earthquake actually performs well... might as well DPS resto, since your AoE healing spells are terrible for about the same time length, too.
In tandem with the class balance, the dungeons tended to progressively get harder as you leveled to where you'd almost needed perfect playstyle to survive (unless you had one of the overpowered classes for the level). I appreciate the dungeons being harder, but leveling is still a learning experience and shouldn't require the polished rotation execution and knowledge of all boss/trash mechanics that some of the dungeons present. I've never seen so many vote-kicks while leveling in dungeons beyond blatant AFKer's. What would really assist in this issue would be to drop the damage of mechanics in many of the dungeons, as the increased health makes the mechanics matter almost too much for a leveling experience.
Also, the scaling of gear seems to work well until you hit WoD. While this is more of a general issue than specifically a dungeon issue, it does trickle over into dungeons, too. The gear stats increase fairly linearly until WoD, where the stats just jump up drastically per level. All fine and dandy, except the content is vastly overtuned until you get full WoD gear, and even then it's very rough (this is post nerf, too). If you thought running dungeons was difficult prior to WoD content, it's just an exercise in futility when you get to WoD.
Don't get me wrong, I did enjoy leveling again, but instead of making questing in the world another option for leveling, it's pretty much the only option without a premade group.