Yes it is still in beta, current version is 0.8, with the full release being ver 1.0.
There are still some features that need to be added, but for the most part it is easily usable as it stands today, I use it all the time (have since version 0.2 - I got the Indie pack for $150, included Designer, Painter, BitmapToMaterial and some pbr textures). It uses a pbr material system based off of the UE4 rendering engine, so the results look pretty much identical after they are imported into UE4.
It’s a really good program, and you can download a free month trial from their website: www.allegorithmic.com/products/substance-painter