I have a purchased version of Lightroom 5.7, and don't find there to be enough advantage to spend $80 on the upgrade. In fact version 5 isn't that much different from version 4 that I have on my PC workstation.
Lightroom is a staple of my current workflow for the last 3 years. Photoshop is only opened on occassion when compositing or layering is needed for a job. Apparently there is a slight speed increase in version 6. I personally am fine at this time with Lightroom on my Macbook Air (cheapest model).
I don't compile HDR images with my style. I do periodically creat panoramics, but already get what I want from Giga Panopro.
Some of the features like the new Slideshow and Web layouts are very limiting for what I want from them.example there are no controls over Ken Burns effect and limited integration of video.
There still is only elementary video capability with Lightroom 6 - so I have to take everything into Final Cut Pro X if I want to assemble clips or do extensive corrections - for Instagram video clips, I find it much easier to open the camera video file in Quicktime 7, grab the 15 sec. section I want, and instantly export it out.
As for the mobile features of Lightroom - which is where Adobe appear to be focusing - it is a Lite version of Lightroom and so I'll stick with using Lightroom on a computer for now, for my serious organizing and editing - and use some of the very useful apps like Pixlr or Fotor, for effortless processing of pics I want to get on the web from my iPad.