Soy products have been the craze for the last few years with some people swearing by them and others condoning them for the long term negative effects on the body. Soy is one of the most processed foods out there, there are however many variations on how its made  and used and whilst some are bad for you, others are ok. Contrary to common belief, asian cultures don't live on soy foods, and when they do eat them, its usually in a fermented form that holds health benefits for the body. 
Soy milk in my books is a big no-no as it is always extremely processed and honestly has no nutrients at all. 
When it comes to Tofu and Tempeh, which one is a better choice? Tofu is a blank canvas, ready to take on the flavour of any spice, sauce or condiment it meets. It comes in a wide array of textures from soft to extra firm and is created by coagulating soybean milk (which in itself is processed) and pressing the curds into a block. Regular Tofu is usually packed in water in the refrigerator section of your supermarket. 'Silken' Tofu is packaged in a box and doesn't need to be refrigerated, it crumbles more easily then the regular one and is used most often in sauces and dressings. These versions are heavily processed and not the ideal choice for regular Soy consumption.
Tempeh is much less processed then Tofu, which makes it a smarter choice on a regular basis. While Tofu has practically no flavour and is soft, Tempeh has a nutty taste and firm texture. It is a great choice if you're trying to mimmick the taste of meat in your recipes and is produced by cooking and fermenting whole soybeans and then pressing them into a dense patty (you can actually see the soy bean in the product itself as in the picture below on the left). I also just want to mention that fermented foods are great for us because they increase good bacteria in the gut. Tempeh contains about 35% more protein then tofu and about 7 times more fiber too! The reason for the higher level of nutrients is that it is less processed and has therefore retained more nutrients from the original soybean. You'll find it in the refrigerator section of your supermarket.

Soy has been the craze for the last few years with the media and Soy industry heralding it as a health food. Many people have made the switch to soy products, soy milk, and have even put their babies and children on soy milk.

SOY IS NOT A HEALTH FOOD, it does not cure or prevent disease and has not even been proven safe yet... In fact many governements including the french government have issued health warnings against Soy (the US government has not yet followed suit succumbing to pressure from the Soy industry).

There are a few things that we do know for sure:

Soy is THE most processed food out there and devoid of most nutrients found in the original soy bean; Soy contains phyto-estrogens that are not real hormones per say, but most certainly act like hormones and can cause significant endocrine disruption in the body. They interfere with the normal production of Estrogen, Testosterone and other hormones in the body. We know for sure through several studies that Soy estrogens are NOT weak, despite what the media claims. They are potent and can affect your whole endocrine system, your thyroid and children's normal development. It is very important that soy products are avoided during child bearing years (there are many studies that indicate they contribute to infertility), during pregnancy (as they affect the normal development of the Fetus), infancy and puberty (they affect the normal growth of a child by dirsupting the hormone levels in the body) and finally around menopause.

My recommendation is that you eat soy foods occasionally in the form of Miso soup and tempeh for example which are the tradional forms. Do not make it part of your staple diet in the form of milk and other heavily processed forms...and please do not give it to your children! There are just too many well-documented risks and they far outway any potential benefits.