My dad paid half for him back around 77 or so. A lot of hours on that guitar. He has another D28 that dad had and gave to him, but he rarely plays it. He said his just feels right. Check out some of his other stuff on YouTube. Dude has skills.
Of course, any of the wood guitars sound better with time, that is what makes them vintage. I have my grandfather's '67 Gibson J45 and it is an amazing guitar, sounds so awesome but I don't play it much. I keep a humidifier in it and keep it in the closet. Until I start missing him then I will get it out and pick a few tunes.
If you know your pent and diatonic scales and slides then you have all you need as for a knowledge. Only 12 notes to be played, the rest is in your head or soul or its not.