They're great. I've had them for a couple of years. See Martin's comments above.
That only happens if you are taking a superphysiological dose (i.e. dose greater than your body would ever produce on its own) which shuts down your natural production. It is not permenant, though. If you have low testosterone what your are prescribed will only be enough to put you back into normal range towards the upper middle of it. Do not waste money on creams/gels/patches. They are overrpcied. A 10ml bottle of 200mg/mL testosterone costs $110 cash in most of the USA and it will last you between 10 and 30 weeks depending on the dose you are given.im afraid to try it because i heard it stops your balls from working on their own. but then again im in my 20s. however im not high in T