LexisNexis calling this a "Hadoop alternative" is pure marketing, grabbing on to the tailcoats of fashionable tech. HPCC is not a MapReduce framework. It's not a framework at all. Instead of letting you plug in existing code in arbitrary languages to process your data, everything you do has to be rewritten from scratch in a new declarative query language called ECL ("Enterprise Control Language"), which isn't supported by anything but HPCC. LexisNexis even tries to position this as a feature, describing HPCC as a "complete" and "homgeneous" environment.
The success stories given in the HPCC white papers are almost exclusively government agencies, and what few commercial customers there are seem to be using HPCC to replace legacy mainframe systems. There are, notably, no examples of companies that previously used Hadoop and switched to HPCC.