I'm diamond (I know thats not special) and playing in silver atm on a smurf.
Here are my observations. Maybe it will help someone.
(for the record it's a pretty fun, relaxing environment to try out new champions.)
There is so much early fighting in all lanes nonstop that no one gets much CS. Even if you think you want to farm it up, it's virtually impossible because you HAVE to respond to all the aggression on both sides or you will fall behind. There almost isn't a laning phase compared to diamond. For this reason, late game scaling champions are much weaker.
Jungling seems to be ridiculously OP. Nobody wards, and if you bring a little CC with the laner or the jungle, you can continuously get early kills basically for free. This leads into a massive snowball. First blood is usually at 3 minutes or before. That same laner that dies first will then usually die again soon.
There is little to no care for objectives before final pushes are started. People don't wan't to defend turrets or take dragons. I have solod the dragons many times as adc and mid lane (depending on my champion and performance) without the jungle ever responding.
Duo/Trio queues are ten times more toxic. They only play together and refuse to even acknowledge another player. This isn't quite so bad in higher rated games.
The picks are disgusting. Every game has yi, tryndamere, garen, shaco, and yasuo. I see so many champions that I haven't seen in ages. I'm not sure why people are so dedicated to these champions that offer so little.
ADC is a lot harder to play (I'm not an adc main and I'm bad at it so this may be biased) because you constantly get odd support picks that have no clue what they're doing, like sion support or lee support or rammus support. It makes for an odd lane. Supports also don't ward very often here.
There are a number of players you will encounter that aren't just having bad games. They belong in bronze 5 but are somehow a bit higher? Not too surprising I guess. They do things like build full damage top laners that are actually tanks when losing, and do less damage than, say, an alistar support. They usually end a long game with around 10k or less, and would be better for the team if they went afk as they generally feed through the nose. You never know which team this player will be on, but he's In most games.
No one even tries to pay any attention to what the team needs composition wise. You could have an ap carry mid, but that jungle is going to lock YI and then top is going to lock Quinn. It only matters if the game gets late into teamfighting, which happens more often than it should given how much the games snowball in one direction.
Which brings me to my final point that ties with the last and a previous, no one pushes objectives or groups before like 30 minutes it's a given rule. You cant force the people to group. You cant force people to take free objectives. It's very peculiar.
Anyways I found it odd. I'm actually struggling to carry quite a lot and doing incredibly poorly (in my defense I'm learning new champions and some of them aren't champions that carry well such as kassadin (who is also a late game champion.)) Don't ask me why I'm learning kassadin it seems like a bad idea. I guess it's just fun.