well, it's a strange herb which can take a while to learn how to use correctly. its effects can depend on a lot of factors like which strains you use, you personally and even what mood you're in.
I'd advise you to do a fair bit of research on kratom and if you want to buy some thekratomforum.com has a list of the good vendors (never buy from Head Shops)
if you're used to hard drugs it probably won't do much for you though - I believe a lot of people use it to taper off opiates.
it's far safer than illegals though which makes it all the more crazy that the fucking idiots are trying to criminalise it