I used to use this quite frequently as an energy boost but have since stopped. To be frank, this will most certainly give you energy, but it's a very different type of energy than most are used to I imagine.
Phenylethylamine (PEA) is, under normal conditions, rapidly metabolized by enzymes in the gut - within 15m, the body can process a small dose into nothing. So, you are left with two options - overload the capacity of the enzymes in the gut to break down PEA or selectively knock out a specific set of enzymes that are particularly effective at neutralizing PEA.
The first strategy is what standard dosage does - the minimal amount to give you an energy boost beyond 15-30m. However, if this is deviated from, it will increase energy, but it's a shotgun blast of amines into your body - i.e., it's the perfect means to a hypertensive and inflammatory crisis. The second strategy works well, however, requires a complimentary supplement that has other risks involved.
After using this for over a year and seeing what it does, I don't think it's a great product. However, it does, by itself, work - I would just exercise caution when supplementing with this.