I have a couple of Mormon friends (I'm hispanic) and they are some of the nicest people I've ever met. Honestly, I've yet to meet one rude/abrasive mormon. Not saying that they don't exist, just saying I've never met one.
About the only really annoying thing is the fact that they (literally) think it is their mission to convert everyone and anyone. I made it really clear to my friends early on I was a godless heathen and while I don't mind discussing religion, no amount of persuasion short of God himself appearing before me (and allowing me to take pictures of course) was going to change my mind. Once they realized I was hopeless, they left me a lone.
And as far as the whole cult thing goes... it's a religion. Nationally recognized by the United States of America. Scientology is a cult.