Progesterone may be useful for brittle nails, apparently and also dry skin. It promotes the development of certain structures in the breast tissue, aids in fat accumulation, can help improve mood in some while having the opposite effect in others. Helps some sleep better, can lead to insomnia in others.
Personally, I'm not sure if it's doing more good than bad. I've taken it 2 years now, at quite a high dose. I do notice my hair and skin getting much softer just when progesterone hits me (I can tell because it also makes me "high" and sleepy), that I need to go pee shortly after, that I suddenly get hungry for chocolate and sweet stuff and that often, I start getting a headache. I do think it helps me go to sleep faster, reduce anxiety if I experience any and makes me feel good for 1-2 hours at least, I'm giddy and loving. On the downside, I suspect it may be making me a little heavier than I would like to be, makes me look bloated and may be the reason why I'm not experiencing as much breast growth as I should since it also opposes estrogen, making cells less sensitive to E, and increasing conversion of estradiol to the weaker estrone. I also notice other effects many hours after I take it which may be due to the decrease in levels, like decreased appetite and irritability/depression. I also think my skin actually got drier when I increased my progesterone and that on high E alone, my nails became stronger. So, I don't really know what to think anymore.
I could reduce my dose by half if I want to (as per doctor) and see what kind of difference it makes. Would definitely help me see if it's more beneficial than not, for me.
If your doctor agrees to prescribe it, then you could try it and see for yourself. Continuously, you might have less ups and downs but some apparently do better cycling it. You need to discuss this with your doctor. I take it with food so it has double the effect and absorbs better. Fatty foods are especially useful for increasing absorption as progesterone is lipophilic. I take it twice daily as well so that levels be as steady as possible.
In the end, it's really an individual thing. Some like it, some don't.