In my opinion, the new system is fairly nice.
Though a few things need tweaking.
First is the gain and loss ratio. I like how fast it is to rank up and all that jazz but the point loss is ridiculous. I played two games the other day and gained a total of 26 points. Today I play a game and lose 20 points. Someone please tell me that is nuts.
Second is who you play with. For example I am in a Silver Tier Division V and I get paired up with Bronze Tier Division V's. I think Riot need to change it to where you play with your own Tier. Just to prevent trolls. Cause we all know that some Bronzes love to troll.
Last is a friend comparison tool. Just to see where you stand with your friends. Example I am in Silver and most of my friends are in Bronze. (Which is hilarious cause my friends are all better players than I will ever be.)
Yeah, so these are just some of my ideas. Feel free to leave me your ideas below or let me know if any of my ideas are flawed.