Well I played ARAM today. It was very frustrating, since I constantly got screwed in champion or people select. I got terrible players like you wouldn't believe. At one point I even got to play 3 v 5. I played 15 games total, won 3. Not a normal situation, for me at least, but maybe I am a bad player.
And then I got to play this game, screenshot in the attachment. Seriously not cool. How do you fight 4 healers. We didn't even got to see their outer tower, let alone to get close to them. As soon as did some damage they quickly got healed up. In the process we got barraged by Janna + Nida + TF, and even if we managed to survive those Sona and Taric would stun us and that would be the end of every team fight.
I get it that it's supposed to be random, but really it is not. I often get same champs to play. I don't remember the last time I got to play MissFortune or Fiddlesticks or even Jayce.
Also there is an issue of people leaving in champion select. I don't always get champ that I want, but I never left because of it.