Since most diet pills are just regurgitations of eachother, it is fairly easy to provide information based on the ingredients and based on this ingredients, I'd stay far away.
Yohimbine should only be taken under doctor's order for erectile dysfunction, it hasn't been shown to be effective for weight loss yet...
Higher doses of oral yohimbine may create numerous side effects, such as rapid heart rate, high blood pressure, overstimulation, insomnia and/or sleeplessness. Some effects in rare cases were panic attacks, hallucinations, headaches, dizziness and skin flushing.
Yohimbine in combination with drugs that inhibit the reuptake of norepinephrine, such as dextromethorphan, tramadol, some antidepressants and central nervous system stimulants used to treat ADHD, can cause a hypertensive crises. This is due to those drugs in combination with an a2 receptor antagonist leads to too much norepinephrine in the brain, which causes blood pressure to spike to dangerous levels.
More serious adverse effects may include seizures and renal failure. Yohimbine should not be consumed by anyone with liver, kidney, heart disease, or a psychological disorder.
Citrus Aurantium is very similar to ephedra and sadly has the similar effects that caused Ephedra to be banned in the US
Like most dietary supplement ingredients, bitter orange has not undergone formal safety testing, but it is believed to cause the same spectrum of adverse events as ephedra. Case reports have linked bitter orange supplements to strokes, angina, and ischemic colitis. The U.S. National Center for Complementary and Alternative Medicine found that "there is currently little evidence that bitter orange is safer to use than ephedra." Bitter orange may have serious drug interactions with drugs such as statins in a similar way to grapefruit.
Mix those 2 with a high dose of caffeine and a couple other ingredients that haven't been tested well and it seems like this is a law suit waiting to happen.