You shouldn't have much trouble. They've streamlined the game a LOT in the past 4-5 years. Take stats, for instance. Realistically, any piece that has more of your class' main attribute (Int, Str, or Agi) is going to be better. And now Str and Stam variables are tied, generally, to the ilvl of the item. Because these are so heavily weighted, you are only ever gearing via sidegrades if they are the same ilvl with different secondary stats. This is rarely something you have to care about when leveling.
The second major change is that you are forced into a single talent tree at level 10, but get some very strong bonuses for doing so. I dunno if they rebalanced them, but a year ago when I last played these abilities were usually HEAVILY overpowered for the level.
Another thing is the Dungeon FInder tool. Now, you can go LFG using a cross-server group finder that will automatically construct a group and then port you to the dungeon. This makes keeping ahead of the gear curve easy, because you can always be queued while questing. And being ahead is nice, because they upped enemy damage by quite a bit.
Also, combined with their efforts to increase damage output by healers and tanks, they are fully viable while leveling. Combined with super fast queue times for dungeons, they actually level faster than DPS do now.
Anyways, you all are horrible, @#%^ed up people
Never underestimate the healing power of a massive dong.