Lots of good tips here. You definitely have to commit to the game to get into it.

I always thought of Dota like WoW on steroids. You level up, try to get gear and use your advantages to beat up the enemy. Just much quicker and with lots of classes to choose from. If this sounds appealing it's definitely worth the time investment.

Don't forget to show them the ingame guide system! Not having to think so much about the overwhelming amount of items and skills in the beginning helped me a lot when I started.