I keep hearing different ideas on whether you should go to this world. I just turned 20th level and was wondering if this place was worth it. Does it give good experience and is it even worth me paying the crowns for it.
Grizzleheim is definitely worth it. It is a fun world in its own right. You get a decent experience boost, though not huge.
But GH is also necessary later on to get access to Wintertusk. Wintertusk is needed for school spell quests. Wintertusk is also probably the best realm in the spiral, both for fun and for equipment. Wintertusk is also a great experience boost.
So yes, do GH, both for the fun of it, and for the access to WT later on.