It's odd to listen to about 140 hours worth of material in the car (Audiobook versions of the Dark Tower I-VII) Now that I'm done, I feel like I've lost a friend, a driving companion. Roland, Eddie, Jake, and Susannah, and Oy of course, won't be accompyaning me on my way to or from work anymore.
Also, I don't know if I recommend reading/listening to the 'coda' of book seven. I think that short coda makes the series entirely different. So, read the series, stop at the coda, think about it for awhile, and when you're ready to have a much different viewpoint of the whole series, read the coda.
So in my standard Method of Operation, I am now 'obsessed' over the series. I want to read all the cross-materials on the series, see the buildings at 2 Hammerschalt Plaza (860 UN Plaza supposedly), and went to see the Dark Tower Website. As for the artwork, I really like the work of Michael Whelan.
Other Dark Tower links: