[Chojin]

Level 20 doesn't mean a lot, really - It just means that your skills are maxed (aside from attribute quests). It'd say at least a third of the game takes place after you hit level 20, assuming you didn't just run through missions.

All future GW expansions will have level 20 characters in mind, you can only go to the Underworld and Fissure Of Woe if you're level 20 (special dungeons with the best drops in the game), and you should only participate in GVG when level 20.

So in reality, most of the meat of the game happens after 20, but you can't level up anymore. Think of levels 1-19 as the pre-season.