We've been selling Denise interchangeable sets in our store for the past 8 years or so. They have changed a bit during that time. I know early on they had rougher needles and occasional seams. But these days, the needles are very smooth. The smaller sizes that make up the right side of the case are glossy in appearance. They will never be as smooth as metal, but they are certainly smoother than bamboo. The tips are a bit blunter than say KnitPicks, but no blunter than KA, Clover, or ChiaoGoo wood or bamboo needles. I knit continental style and don't feel the blunter tips slow me down. I find with the KP needles, my finger tip gets sore after a while.
The cable themselves, while thicker, are remarkably flexible in our opinion. Amy likes the set because this is the only set (that we are aware of) in which you can create a 17-inch needle and comfortably knit from it. 17-inch being a very convenient size for knitting many common items such as hats. The thickness of the cables would be a challenge with magic loop knitting, where a thinner cable would be an advantage.
Amy and I both knit a fair amount on Denise needles. I have a Denise2Go kit which I really enjoy using. I'm sure we have sold over 1000 sets and I can count on one hand the number of returns we have had. So I know there are fans out there. But these days there are also a lot of choices and each appeal to people in different ways. It's all really a matter of preference and what you like.
On important reason we choose to carry Denise needles is that they are the only manufactured interchangeable needles that are made completely in the USA. Everything else is made in India or China. The Denise company is a wonderful family run business located in Virginia and always a pleasure to talk to and very accommodating. We feel good supporting them.