Graphical dataflow programming is super powerful. It's the bread and butter of Ab Initio Software, which powers the data infrastructure of many of the world's largest corporations. I'm glad to see an open-source project entering that market too.
Years later, I had to maintain a software application built by a bunch of idiots who thought it would be a great idea to use LabVIEW as their GUI layer (because apparently that was easier than learning/using a proper GUI toolkit). This monstrosity communicated with a back-end running on Solaris via LabVIEW's freaking horrendous TCP control. The whole thing made absolutely no sense. Though LabVIEW did provide a rather nifty visualization of spaghetti code.
I suspect this was a resume-padding exercise for the original authors. Rumor had it that one of the engineers responsible for the decision to use LabVIEW had been hired away by National Instruments. And we all cursed him.
So anyway, after that experience I'm pretty well prejudiced against graphical 'programming'. I took one look at this NiFi thing and said 'Ha! Nope.'
Does it have the ability to integrate with Hadoop ?
<disclaimer: I'm an employee of one such vendor>