The community can be unpleasant, but is generally forgiving and open to new players. There is a pretty steep learning curve, and the lack of a decent tutorial makes this worse. Balance and maps have improved, but I still find long, 3-4 hour stalemates fairly common in large matches.
King Arthur's Gold is a truly unique experience. There's something for everyone in this game, whether you enjoy building massive fortresses, killing hordes of enemies, or role playing on a giant map with different races and factions. There is a decent competitive scene if you're into that sort of thing. Matches are usually full of people with mixed experience, so newer and more casual players can enjoy themselves as well. KAG is one of the most unique, addictive, and challenging games that I have ever played, and is definitely worth checking out.
All things considered, King Arthur's Gold is probably the best ten dollars I've ever spent on Steam.