By consuming this essence, the ultimate proof of the power of pure intellect, you transcend all known limits of intelligence.
*Your intellectual faculties (mental capacity, mental focus, calculation, computation, cognition, competence, memory, wit, ingenuity, creativity, mental perception, learning capacity, deductive reasoning, inductive reasoning, visualization, analysis, instinct, intuition, self-awareness, composure, mentality, multi-tasking, etc.) are increased to the absolute maximum possible in all existence, and perhaps slightly beyond even that.
*Your intellect is not only exponential but also transcendent and flawless. The only possible cause for your making a mental error would be the garbage-in-garbage-out principle, because your cognition is perfect within the limits of the data available. Even a supermassive quantum-computing Matrioshka Brain would be less than a protozoa compared to you. Your processing capacity also scales up without limit when necessary, to the point you could effortlessly solve any finite algorithm in a single unit of Planck time.
*You no longer have a subconscious, your intellect being enhanced to the point that you have a "supra-conscious" mind instead. Like a subconscious your supra-conscious is capable of performing both mental and neuro-physical actions as background tasks without needing you to actually focus on them (although your heightened focus and multi-tasking could let you simultaneously concentrate on any number of separate things if need be), but unlike a subconscious you may have your supra-consciousness execute almost any task or tasks that your conscious mind would be capable of, however complex, and have your conscious mind exert total control over its functions when necessary.
*Your supra-consciousness also gives you instantaneous and effortless access to every iota of every quality and characteristic that you possess, and every scrap of knowledge that you ever have acquired or ever will acquire. This grants you, among other things, a perfect memory with unlimited storage that is retroactive across your entire life to date to a degree bordering on postcognition.
*Your supra-consciousness also allows you to fully comprehend and control your emotional state. While you still have a normal capacity for emotion should you so choose, you never become emotionally compromised or traumatized by anything unless you allow it. Furthermore, your mind is capable of processing, resolving, and overcoming trauma with almost instantaneous speed when you focus on doing so, and will also autonomously use this self-repair capacity to return you to at least adequate mental functioning should your mind somehow be too catastrophically damaged to focus.
*Your intellectual expansion will not materially alter your personality against your will, although you may of course apply your newly heightened capacities for self-awareness and introspection towards the goal of personal growth and change if you want to. Otherwise you will still remain "yourself" as much as possible despite your new level of sentience, without risking the death of personality that can sometimes accompany transcendence.
*On the principle of a 'sound mind in a sound body', this essence grants you perfect health and average fitness for a member of your species. The heightened capacity for conscious bio-feedback that your supra-consciousness provides allows you to, among other things, maintain your level of physical fitness without deliberate exercise.