Just be aware this version only includes 9 characters (Season 1 + TJ Combo).
There are two further seasons of content included with the Definitive Edition.

why cant they just release a full version on disc
every timr i play the damn game I cant select the characters i could select time before

heres one review sadly
1.0 out of 5 starsDON'T BUY THIS IF YOU'VE BOUGHT ANY PREVIOUS VERSION OF KI DIGITALLY FROM THE XBOX STORE!!!
By Russell Quayle on 11 Oct. 2016
The Good: -
Like most, I was really looking forward to this, to get everything in one package, soundtrack and all.

The Bad: -
However, what I actually received was something completely unexpected, basically a very lazy put together product. For any other fans of KI, something that isn't explained anywhere to you prior to purchasing this is if you have had any version of the game before the definitive edition was released? Should it matter? Ordinarily, no, but, when it comes to the Killer Instinct Definitive Edition, it most certainly does. If you have ever purchased any version of Killer Instinct digitally from the Xbox Store, then please read on.

The Ugly: -
So, the first thing you should know about the definitive edition is that the game isn’t on the disc in quite the way you would think it would be, I expected to pop the disc in like any other Xbox One title and after a short to medium install, play the game. Simple right? Nope, basically you pop the disc in and it just installs all the individual packages it would download and install as if you bought the game/content straight from the Xbox Store and OMG it is slooowww. I have never seen 40 something gig take so long to install from something other than the internet before! However, this isn’t the biggest problem, I had previously purchased the Ultimate Edition of Season 1 from the Xbox Store. So even after installing everything from the disc, everything beyond the Season 1 content is still locked to me and it is asking me to purchase it again. So I cannot play anything beyond what I had already. The disc basically assumes you have never had any version prior to it! There is no unobvious or hidden activation process to unlock it either.

The Definitive digital edition is the best option for new buyers, It was recently reduced to £16.99 for Gold members and will likely be on sale again at some point. Thankfully that version is now compatible with Windows 10 too!

heat added as £4.99 very good price,but game doing definitive version for £14.99 currently & so much more on that so I opted for that version

I remember reading that review, the person didn't know what they was doing.

If you have digital versions of an xbox one game and decided to buy the retail disc then always remove the digital version first then install the retail disc. The person didn't do this hence the problem they had.

Its a small bug MS hasn't fixed as they don't expect anyone to buy a retail disc if they own the digital version already.

Yeah, I had this problem when I bought the Tales From The Borderlands disc after getting a digital copy of Episode 1 for free. Took me ages to work out what was going on. Strange that they haven't managed to sort that out.

It's licensing. Your gamer tag has licenses for the games you own digitally, if you install TFTB you'll notice it's full title is 'TFTB Episode 1: Zer0 Sum' and the same on your achievements. Usually it only happens with TellTale games that you then get a physical copy of after playing the demo without deleting the version that your license locks you out of the other episodes. It's not an issue or a glitch and Microsoft has never admitted to it, just hearsay. Your disc has a specific license for all 5 episodes and it is simply clashing with your digital license