I liked DK in the beginning, but lost interest over the summer. A friend of mine who has seen Ryuki flat out hates the show. I don't go that far but I am frankly getting a little tired of the acting and choreography this show uses. Not to mention just how silly the plot can get. Chris having a chronic illness? Good idea. The illness being..... asthma? Come on, they couldn't have done better than that? Especially when you later have the plot point of JTC tempting him with a cure. I'm sorry, you have to find a more convincing disease than asthma, something lots of people live decent lives with, to pull off a plot like that.
You're better off watching Ryuki. That show has a little more "power" to it than DK. The only two things I can really credit DK on is:
1) The "Lonely Kamen Rider" premise. We have Len, essentially the last of his kind, in a world that is not his, fighting on against all odds. That's the romantic appeal of Rider right there.
2) Ren and Kit's relationship, which seems almost reminiscent of Jou Yousuke and Diana in Spielban. (This partly ties into the first point.) Two souls who have no one else in the world to turn to but each other. Sticking together is the only way they can survive.