Flax is good for you, mostly due to the omega-3 content. Our primitive ancestors lived on free-range meat and gathered nuts and occasional tubers/vegetables/etc. They ate a lot of omega-3 fatty acids due to their varied diets along with the varied diets of their prey. Modern Americans get about 10-40 times more omega-6 in their diet than they get omega-3. This may sound unimportant to someone who has no idea of what essential fatty acids are, but it is. People think eating a varied diet is having a salad with dressing with their greasy quarter pounder and large fries (loaded with omega-3 deficient hydrogenated oils). True variety will give you the omega-3s you need, but who gets true variety these days?
Omega-3 fatty acids are found in cold water freshwater fish, especially fattier ones like salmon. It is not recommended that you supplement omega-3 from fish oils, because toxins tend to accumulate in animal fat very easily. Two to three tablespoons of crushed flax seeds will provide a decent dose of omega-3s in a day, and there is no chance in hell it will hurt you unless you happen to be allergic, which is possible.
Omega-3 and omega-6 fatty acids are used to create cell membranes and many hormones, including the all-important prostaglandins that regulate your hormonal cycles, including patterns of inflammation. You can do no harm by eating ground flax meal on a daily basis, and considering the highly deficient nature of the American diet, it's a good idea. Nobody's saying you should eat nothing but flax meal, and keep this in mind -- any foods that contain pre-ground flax are a waste of money. The flax should be eaten within hours of grinding, as the omega-3s are very reactive and will oxidize into BAD, rancid fats within very little time. The biggest problem with our bad ratio is that omega-3 and omega-6 acids use the same enzymes to metabolize, so if you have an excess of omega-6, the few omega-3s you have won't even be consumed.
It is recommended that you have a fatty acid balance that is approximately 4:1 omega-6 to omega-3. Omega-6 is found in just about everything thanks to corn, canola, and soybean oil. Omega-3 is nearly impossible to get in ANY processed oil, because it is polyunsaturated and tends to be destroyed in oil refining processes (extremely hot temperatures are used to produce that pretty yellow color).
Flax does not contain gamma-linolenic acid, which is also essential and highly deficient in the American diet. Curiously enough, the hemp plant Cannabis sativa bears seeds with a nearly exact 4:1:1/4 omega-6 omega-3 GLA ratio, making it nature's perfect fat -- assuming it's the only fat in your diet. Since most of us can't subsist on pure hemp oil, it's better to take flax since it contains more omega-3 than omega-6, thus balancing our off-kilter diet.
And yes, you need omega-3s. They don't call them ESSENTIAL fatty acids for nothin'. If you've got bad hair, dry skin, or inflammation problems, take some friggin' flax already, and toss a hemp or evening primrose supplement along with it to supply some GLA.