I'm Back! I need a TL;DR

So I stopped playing Dota and went over to League (yeah I know) around 6.88 because I was just so bored. Volvo took forever to release new heroes, there was a Pudge every game (and according to Dotabuff there still is...), the community was really toxic, and I couldn't seem to climb at all.

Decided I'd go check out ol' Dotafire after all this time, a website I visited almost every day several months ago, and just WOW. 7.00 looks pretty spicy. Guess I chose the wrong time to leave. Anyway, I'm asking for a TL;DR so I know what I'm getting into now that i'm playing Dota again. Who's strong? Who's weak? What are the pros playing? Will people still hate me for using Slark? Basically all the big changes between now and 6.88.

Thanks,
Blubbles

EDIT: WOAH THE NEW MAP
EDIT 2: I MISSED TWO HERO REVEALS? VOLVO... wait a sec does this mean Volvo might actually take community input for hero ideas?