A month is FAR too early to tell. You only start to see a response to finasteride after 6 months or even a year. Whether your Finpecia is legit depends on where you bought it from. Some internet pharmacies have a fairly good reputation (Inhouse Pharmacy, United Pharmacies, Merlonipharma) while others are a bit dodgy. The WHO estimated that 50% of drugs bought online are fakes.
I got mine from United and inhouse. I was worried about the efficacy of Generic drugs. I've been reading that there has been little or no clinical tests done on the efficacy of Finpecia. Just wondering if anyone has used it and experienced any success at all. That WHO statistic is worrying!