I'm 38 and have had no loss of libido. I've been on "full" doses for over 2 years and have not had any real issues, other than Medroxyprogesterone. I had a horrible reaction to Provera (Medroxyprogesterone), but it went away as soon as I switched to Prometrium (micronized progesterone). If anything my libido had increased. I'm not certain if it was the hormones, or if it was my comfort level with my body... but it has been a wonderful experience. There was a steep learning curve with some of the heightened emotions, but I figured it out in the first few months.
I don't think that the negetive side effects are all that common. There are a few medications that have a higher incidence rate of negative side effects, but thankfully there are many alternatives that clear up the issues. Medroxyprogesterone, and Finasteride have given negative reactions. Spironolactone is fairly mild, but it will make you pee a lot. Some have a problem with the highs and lows of estrogen pills, but there are also injections, patches, and pellets... etc. If you get a good doctor, they'll ensure to find a combination thats right for you.