Depends on what you want from the games you play if your a beer and pretzel player just happy to throw dice around with your mates then generally yes there shit as your forced to play random people many of who are the complete opposite of you.
If you like competative play then you may enjoy the tourney scene as you'll probably come up against some decent tough competition unfortunately in my experience you'll also meet a fair few dicks with bare minimum social skills which makes the hour or so your playing them an irritation rather than an extension of a fun weekend.
If you're a beer 'n' pretzels guy, I would suggest that tournaments probably aren't the event for you. Look for a campaign weekend instead, you'll enjoy yourself much more at a non-competitive event.
In my experience, most people are pretty well mannered at competitive events; there's only ever been one or two people I've encountered that are legitimately either cheats or aggressive. The vast majority of people are fine, and frankly you're quite likely to come up against dicks outside of a tournament- that's not an element of competitive 40k, it's a part of life. The only difference is in how you decide to handle them- you can either let it get to you, or you can proceed to utterly manhandle their cut-n-paste army that they have no idea how to play.
I recommend the second option.
"Knowledge is knowing tomato is a fruit. Wisdom is not putting it in fruit salad."
Also known as BaselessElm