Well, it's definitely less popular for people looking for random sex, what with smartphone apps and all. Not sure about other things.
I will tell you with very direct experience that their _monetized_ sections are growing quickly (due to more monetization in more cities), and the overall user base is growing with overall internet usage.
This needs citation also.
This as well.
I don't have 3rd party research but I've been personally logging the names and locations of paid sections for the past two years.