@steadying: @seikenfreak: I'm Aegis Heaslip on Ultros. I had a link to my character profile in the first caption but it looks like the GB editor ate it. Don't worry, I'm in the Giant Bomb Free Company.
I figure I'll still mostly be doing dungeons with randoms until level 50 since I'm coming in so late. I have yet to have a bad dungeon experience -- someone (usually the tank, FWIW) seems to always know what they're doing, and as a healer I'm naturally in a passive position. On the other hand, I have only the vaguest sense of how to clear the dungeons I've run -- I've spent most of my time following the group and/or staring at the party list.
@steadying: @zeik: @rorie: Anecdotally, I've hit CNJ 30 and ARC 15 with a month of on-and-off casual play. I've been playing very inefficiently -- exploring around the towns, reading everything (and it's a pretty wordy game), doing excess lower-level quests, etc. I bet a dedicated MMO power player could hit 50 in a month without playing that excessively. Hearing that the leveling process was fairly streamlined was a big factor in my choice to give FFXIV a shot.