If biotin pills didn't really work I seriously don't think your doctorwould have told you to take them.
Not a Brain, but from all I have read biotin does help with hair breakage and also helps to thicken the nail plate. The improvement in the nail plate is measurable. I take biotin myself. My dermatologist recommended it to help with some hair breakage issues I have been having.
Maybe the Brains will chime in. While you are waiting for their reply here is a post from Dr. Benabio.
Certain nutrients are essential for good growth of hair and nails. Biotin (also known as vitamin H) is one of them. Most people get enough of these nutrients through their normal diet. However, if you are deficient in these for some reason then taking them as a supplement can be beneficial.
If you're NOT deficient than taking extra Biotin probably will do nothing.
In a study (I'll try to find the reference and append it below), Biotin was shown to increase fingernail thickness by about 25%, but it took almost a year of supplementation at a fairly high dose to obtain the results.
@Hoverfly: Very interesting. The study was conducted on people with "brittle nails" so I wonder if any of them had a biotin deficiency. (At least the 63% that saw an increase in nail thickness.)
I've been taking biotin for about a year and its improved my skin and nails but I see no difference in hair growth. I have very dry cuticles and biotin has improved the skin around my nail bed so i no longer get those dreaded hang nails.