"Dying Light's The Following expansion will launch 9th February 2016, Polish developer Techland has announced, alongside - as well as included within - a newly unveiled Enhanced Edition of the game. This is for all three formats: PC, PS4, Xbox One.

The Enhanced Edition does what a Game of the Year Edition would typically do - bundle the game and all downloadable content - but with added relish. The enhancements and added extras apparently took half-a-year to create.
The enhancements include: 

Nightmare difficulty setting
Legend system
Bounties system
New Parkour moves
New enemy attacks and behaviours
Enhanced facial expressions
New NPC models
Improved human enemy AI
Improved volatile AI
Greater firearm variety
HUD and video filter customisations
Audio upgrades
Gameplay quality improvements
Console performance upgrades 
Overall game look and feel improvements
#DrinkForDLC Content

Those enhancements are available to any one who owns the game. You'll be able to download them as a patch if you own the game already, or they'll come with the Enhanced Edition itself - it would be jolly strange if they did not.
Also included in the Enhanced Edition are DLCs The Following, The Bozak Horde mode, the Be the Zombie mode, the Cuisine & Cargo challenge missions, the Ultimate Survivor Bundle, and all the content updates released to date. It's a $60 game, so a full-priced game.

The Following expansion is available either alone or as part of the Season Pass, which will be raised in price to £24 on 8th December. Currently it's £16. Techland announced its intention to up the price about a week ago, explaining that The Following had grown so large it required a bigger price. Alternatively you can buy The Following alone for £16. 

The Following introduces drivable buggies to the game, which can be murderously modified and full-throttled around a giant new map that's the same size as Dying Light's current maps combined, apparently."

All sounds kinda interesting. Games 2.0 really is becoming A Thing.

I might actually get a around to playing this then. New patch sounds great.

The rest of the DLC that's already been released isn't worth bothering with Grem. It's all about The Following.

It's amazingly well implemented - it's the first time I'd seen it in all the hours played so far.

Ha, is a bit like that. Everytime I see an airdrop I just nope the other way. Five zombies. Nope. That area looks a little dark. Nope. Two Rais dudes are wailing on someone, good luck fella.

Just came in here to ask when this bumper 'enhancement' patch is out but i can see g.man's post above.

Great stuff. I still have the city part of the main game to complete so thats plenty of content right there.

Is the combat really, really hard in this or am I just crap? Every fight ends with me losing 2000 survivor points.

Gets easier as your weaponary improves and skills increase. Eventually you'll be swipping through hordes with one hit kills

I want to play this again NOW. So much fun.

Game of the Year.

Started playing this again after a break for my Xmas games. Such great fun - although I'm still too chicken to go out at night.

Been breening around Haran today, gathering side missions, experimenting with weapon combos and ranking up.

There's such a massive feeling of freedom in this game. I don't think there's ever been another game that recalls such a level of involvement with your environment - see a roof/building/antennae you can nearly always climb it.

utterly brilliant.

Sounds pretty stinky G.