While John's resources are extremely good, it doesn't mean they are right for everyone, and it doesn't mean the keyboard isn't useable without them.
Some people are happy with the Korg's factory settings, others are not. I used them as a starting point and did my own setup, and found I didn't need to do an awful lot to make it sound like I wanted.
I changed some drums kits and some style part sounds and levels, changed the STS settings to call up the sounds I wanted called up, then saved to Songbook. Very simple once you get into it.
You can edit as little or as much as you want, and it's not too hard, but there is a learning curve, as with most things.
DonM