as someone who has about 60 days combined /played time on both alliance and horde, im going to warn you not to get your hopes too high.. community is overall pretty nice but you will definitely get groups with people who are rude and obnoxious and utter pieces of cancerous sh*t, on BOTH factions, that is
1 example i can give you is from a heroic daily group i was in a couple days ago, despite being top DPS, doing over 5.5k on last boss some guy from a top guild started throwing insults for literally no reason at all " you're sh*t,r*tard, l2p " then started linking me his ulduar 25 achievements and telling me how good he is and that i should get on his level
Best thing you can do is just be nice and play for fun but be wary as youll meet plenty of elitist jerks on this server.. Best you can do is just /ignore them.