I talked to my endo about Armour because I felt so lousy just on Synthroid. Armour has more than just T4 (Synthroid) it also has T3 (Cytomel). I believe there is also T1, T2 and T7 - not sure what those do... anyway, I am on .125 mg of Synthroid and 17.5 mg of Cytomel. My endo can not control my T3 and T4 levels the way he wants to with Armour or Thyrolar (another combo T3/T4).
There are many opinions on this message board; my best advice is to know what makes you feel the best. My body obviously does not naturally convert T4 to T3 so the addition of Cytomel has mad a HUGE difference FOR ME. Others on here swear by Armour, others yet are fine with Synthroid only.
I have researched the site www.thyroid.about.com and found a ton of information there. You can also subscribe to a newsletter; free. There is also a site about Armour - google "stop the thyroid madness" and you will get lots of information there.
By the way, I had a TT in June 07, papillary and follicular cancer... because of the cancer, my endo wants my TSH to be below 1 - I actually feel best when it is around .05 (more hyper, but no hyper symptoms) -- which strengthens the argument that you can not rely just on blood work to manage your meds; you have to listen to your body.
Good luck!
Julie