Is the game any better now? Quit half a year ago

worse then ever

I'd give it another shot, but just be careful because there are some VERY strong picks atm, (Jayce, Kennen, Nunu, Syndra, Zac)

Well Riot is giving us these things to make up for earlier this season:

Satan Teemo Solo Queue Replay system Snowdown Map New Client Bard Bard etc etc

Nah

pretty much

Balance never has, and never will, exist in this game. That's just how F2P works.

well Devourer is removed, got reworked.

Also we are got:

• Devil Teemo
• Baker Pantheon
• Championship Zed

And for season 7 we are going to get:

• Replays
• Solo/DuoQ
• Sandbox Mode
• Solo/DuoQ
• Winter Rift
• Solo/DuoQ

Regardless of balance, now is a terrible time to come back if you play ranked - the last few weeks of the ranked season is always a very toxic environment.

As for balance... honestly, it hasn't changed much. The mid-year mage update changed things around a bit, and followed Riot's usual theme of some good reworks making champions healthier, and some bad reworks making them even less healthy. It also made something of a mess of mage itemisation (basically, Rylai's is too strong now and everyone builds it, especially DoT users who can really abuse it.)

As for champions, that depends on if you took issue with the "low end" or the "high end". The champions that everyone hates playing against haven't changed, but some of the champions who weren't played much have had reworks to make them more widely playable/appealing (Poppy/Yorick.)