My only experience with them is getting e-mails from Disqus when they've added another generic comment to my blog, linking to a competitor. This has happened about a dozen times over the past several years, so they either do this a lot, or happen to work in my niche a lot (which, by the way, is usually well behind the curve in the digital marketing realm).
They might do fantastic work in other realms, but this alone would preclude my ever working with or recommending them.