I use the AAX version with ProTools 11 on a MBP i7 and ProTools 10 on a Mac Pro.
Unlike other peak/VU-meters it doesn't take up too much resources and causes no stability issue.
It is a worthy successor to my late "TT Dynamic range meter" (which development was stopped long ago and never made it to AAX) that I'd been using for several years. I use it on the master buss to better and check/analyse my mixes for both music and post-production.
In addition to being a peak-meter and VU-meter, it clearly indicates the loudness level (roughly the difference between paek and RMS).
In a time when some favor tough mixes with RMS levels that alter the sound (and worse, inconvenience the listener) with the false pretense to get "a really heavy sound" (which is as useless as ridiculous), the Loudness control allows to get back into a cleaner, less aggressive and damaged sound, with more dynamics ans nuances. In short, it brings back expressiveness and dimensions to your sound.
It is very easy to use thanks to the very sober GUI: you see what you hear and can easily udge your mix (even if of course, your ear has to be your first tool: you don't mix from a VU-meter!).
Some visual settings allow to make reading more precise, but it remains quite superficial, or aimed at working according to some very specific standards.
Pros: I love everything that it does: controlling, plus the purchase includes a total 3 licences (and I got it for $39 instead of $99).
Cons: plugin is not resizeable, which is not a real problem. And I would have loved a view summarizing the mix's general overview, like with more specific tools like the DolbyMediaMeter or Waves' WLS Plus - but hey, they're not in the same price range either!