....of course that can always change.
The Basic Psionics Handbook is a 56 page, 6.81 MB PDF in black & white with a simple color cover. The PDF is secured and disappointingly enough, not bookmarked. The handbook looks great printed out but as a PDF it suffers from the lack of this basic navigation tool. Hopefully this will be addressed with an update because the end-user can't simply add their own bookmarks due to the PDF security.
The underlying problem with Psionics in AD&D was that it was not only practically impossible for a PC to obtain, but it was literally impossible for most players (and GMs) to understand. The Basic Psionics Handbook really does a good job of simplifying the fundamentals. There are two Psionic classes in the handbook, the Mystic and the Monk, and the bulk of the rules really only matter to the Mystic. The Monk's psionic abilities are extremely limited and more of an easy-to-understand tweak to explain how they get so many of those cool AD&D abilities. Also with the monk, those cool abilities aren't given in a specific order, so every 3rd level monk isn't the same. I enjoy this tweak to that class.
In several ways you can think of the Mystic as a more flexible mage-type class, but that is really dumbing it down. Their abilities can be thought of like spells fueled with spell points but those spell points, actually called psionic strength points, can be used for psionic combat. There is an expanded combat sequence on page 28 that makes it easy to integrate psionic combat into the regular OSR combat routine.
The author makes some great GM suggestions when it comes to psionic combat, but I think the whole routine of psionic saving throws, with their modifiers, including a cross-reference chart of attack vs. defense modes, is a bit confusing. I think it'd would play out just fine after the 1st or second psionic combat, but there a lot of potential modifiers that make it clunky.
On the flip side though, I love the one page of descriptions for the psionic attack and defense modes. When you factor in that a lot of this is only going to be needed by the Mystic class and it will be staggered in as they level, since they start out with only 1 attack mode and 0 defense modes....players and GMs will have plenty of time to become familiar with the nuances of psionic combat. I think this would only suck if you were a new GM/player to this at a medium-to-high-level OSR convention game.
There is a great psionic monster section of 30+ "new" monsters and a later page in the handbook (Appendix E) expands upon the CC1: Creature Compendium. I'm a huge fan of the appendices in the handbook and even if I never run for/play a Mystic PC or Monk I think I could get a lot of usage out of the last 10-12 pages.
TL;DR The Basic Psionics Handbook is a good supplement to add psionics to your OSR game, but as a PDF the lack of basic bookmarks impede the sourcebook's usefulness.
Basic Psionics Handbook, which is titled "1501-PX1-NBD-103115.pdf" and it is all bookmarked up! I have to give Richard some credit because he did a great job with the internal hotlinks, especially on the Index and the Psionic Disciplines by Chakra. I could see a LOT of publishers half-assing those two pages (or not doing them at all) and in order to be really useful as a PDF on a tablet.
I feel confident enough to upgrade this product to a 5 star rating after-the-fact.