I have recently tried them, and I wasn't a fan. They initially had a nice clear tone, but as it was stated, the string didn't have the character behind it that my favorite strings do.
On that note I'd like to say I am a complete DiAddario fan. I used them in the 80's, stepped away for years using rotosound 66's, but came back to them after having constant issues with dead string from rotosound.
After discovering the DiAddario Pro Steels, I simply haven't been able to find another string that compares. In fact I feel so strongly about them, they would probably be the only product I would ever endorse. I was offered an endorsement by elixir string once, but I won't endorse what I don't use.
I often flip out strings to try something new, because, well, you never know. But so far, the texture and growl I get from the Pro steels when I dig in I just can't find with anything else.
Having said that, I felt the nyc strings were a good compromise, almost a hybrid between a nickel and steel string. They were very clear, had a nice body, and were easier on the fingers. (I'm playing a bass strung with them now, so I'm trying to be as accurate as possible)
They did have the nice piano sound I like at first, but they seemed to die a lot faster than the pro steels. It's not a bad sound, but they just lost that shimmer I love.
Tension was very comparable, but was looser, much closer to DR Brites. I prefer a higher tension string so they don't get floppy when I get aggressive when I dig in to get the body of the sound out of the string. These had a little less. Not enough to be annoying, but enough to be noticeable.
The big let down for me was the character. My beloved pro steels have this great ability to be very smooth when played lightly, but have a great midrange growl when I dig in. It's a sound i chased for many years. I had it with the rotosounds, and the ProSteels, but it's not there with the nyc's. They are much smoother and more pedestrian.
If you like nickel strings, but crave a little more chime, these would be a great choice. Additionally, if you are out off by the roughness of SS strings, these seem smoother to my touch and definitely a better feel than the rotosounds.
They mellow a lot faster than the pro steels, but still have a good sound. They aren't dead by any means, just more mellow than my liking. Still, they have a good sound.
They are definitely worth a try if you like a smooth sounding SS string.
As a bonus they came with a sticker, just like the old days with Diaddario!