New quests every 5-10 levels until lvl 40-50ish. The main problem that I have with this is that it is a side world, but necessary for a spell at level 35. Not good for those with crowns or limited memberships.
Experience is also bad until Wintertusk, but the spells that you can get are EPIC. Doing part of WT is required for getting your level 72 and 75 Avalon spells.
It is a side world from the main quest storyline. It contains side quests including some for full character development.
Trying to develop an archmage level 80 wizard, or completing the main storyline by purchasing one area at a time with crowns is definitely not the financially economical method. You would be far better off getting an occasional 1 month membership and playing your heart out, then purchasing only your favorite areas with crowns for long term enjoyment. That way there are entire worlds you could play through (one time only just to get your character through) without purchasing it permanently.