I'm pretty sure that the main reason I like opiates/opioids is the mu-opioid receptor action, which kratom does provide me in high enough doses, so yeah it keeps me somewhat satisfied. But, does it get you high like heroin, oxycodone or even buprenorphine would? Nope.
I'm not sure if it would entirely remove WD but it does ease them for me, without a doubt. I know other IV heroin users with hearty habits who've found success with kratom, too. The problem with kratom is that it gives you a little satisfaction but in doing so it reminds you of the "complete satisfaction" you used to get with hard opiates, so you have to be a little careful with it if you're an opiate addict...