Embrel is a new medication with many uses, one of which is Behcet's. I would recommend that you discuss your concerns with a rheumatologist
Embrel (or as its medically known: etanercept) works as an immunosuppresant. Bechet's is an autoimmune disease, where the body attacks iteslf. Therefore, the medicine to treat this must decrease your own immune system. There are many medicines that do this, the most common of which is steroids (like prednisone). In general, prednisone has many, many negative side effects. As such, in recent years medical researchers have looked different immunosuppressants -- which lead to the recent finding of etanercept. Etanercept works by blocking TNF alpha, a part of the immune system.
There are other medicines that work similar to Embrel. Remicade and Humira are both popular medicine that work on TNF alpha as well. Unfortunately, like Embrel they are new and therefore expensive (although Remicade is somewhat cheaper). Unfortunately they have similar side effects -- the reason being anything that lowers your immune system will cause the same risk of infection (the most important side effect).
Talk to your rheumatologist. Remicade may be an option, but they all cost a similar amount. Embrel should come of patent in 2012, so hopefully it will be cheaper soon. Good luck!