My friend invited me to a custom ARAM match, which was filled within seconds. When in the lobby you can switch with other people if they have the champion, so its all random, but if your not good with adc then switch with the ap champ your friend has, which is just what I did when I switched with my friend to be Annie instead of Yi.
The game starts off with you at level 3, able to get 3 early skills, which I should say in ARAM straight away get QWE depending on champion.
You need to take into account that you can not recall back, and when you get back there is no health regen. The only option for health is pots, spells, or these 4 map items with a very long cool down. 2 past the enemy turret, and 2 before your turret. Getting Soraka may be the best thing ever in ARAM. The best thing is people cant complain to you.
I play ARAM and I get champions I never played before. Either ones I bought that I never even tried out, or ones from the free week. The cool thing though is I learn about the champion by playing him.
So if you want a game where you dont have to fight about lanes or champs then choose ARAM, probably the best new gamemode.
The only downside is because its 5v5 and 1 lane, adc champs with no range are useless against all enemies with range, because usually at all times its a team fight. There would never be a solo fight unless there is only 2 people alive.
Yea, I guess thats all to say. Try out ARAM.