Great plugin: does what it says on the box.
The plugin works as it says it does. Initially I had problems because I wanted to password protect pages and not blog categories but there is a way do this. The support is stellar: fast, courteous and clear. And their library of support articles has excellent quality and referencing. If you are wondering if it is worth the price, it is. Support, reliability and future-proof accountability are here. You won't get that with free or cheap plugins. Save yourself pointless time shopping around, avoid the technical agro spent trouble shooting and just buy it!
I had a very simple need for a photographer's website where the photographs are uploaded as featured images on posts -- create a private password-protected section for some photographs. So we created a category, put those photos in posts in that category and used this to protect the category and those posts. I could have written it myself but this was cheaper (and much faster!). Honestly, a few clicks and it was set.
I needed to build a personal tutoring website, with separate public and personal student sections... I found a couple of free plugins, which promised category protection... and indeed they do, but in a very crude way. At the end of the day I removed them, because while they worked, the resulting behavior was very rudimentary and made the site appear unprofessional.
This plugin looked a lot more promising, so I decided to give it a try... and indeed, it is a powerful and clever tool, that gives professional results. Typing a password leads the user to his personal section, and for admin, maintaining multiple personal sections is a breeze. Search shows only the results from the applicable categories (public and the user's personal section), and the integration of a login function is a piece of cake.
I found a slight issue with the calendar widget (posts by date), where the links on the calendar dates are not filtered out by the category, so clicking on some date may lead to a 'page not found', due to that page being in a different user's personal section. I don't see it as a big deal. In general, I'm quite happy with this plugin, and find it very useful.