Think alot of the rune changes are good/interesting/balancing, the new client needs a few patches to be as good as the old one. And there are loads of crybabies here, me including! but you should really make a Poll on the top of this topic...
If you hadn't abandoned us you'd remember that these forums have always been a moan-fest and very rarely do the topics inspire confidence in anything, particularly humanity. I suggest you man up, come back, stomp us newbs and decide for yourself.
Well the number of people who are on have significantly increased, but honestly between people being divided on 2 active clients and no rank reset Id give it a week or 2 and hopefully everything will be good then.
I'd say definitely wait unless you want to be extremely frustrated at random lock-ups. They need to fix this new client before it's really playable. As I've said before, I've had many games where all of a sudden, I just can't move any of my champs. Worse yet, I can't even surrender, so to the other player, they just think I rage-quit.