Kratoms one of the most intriguing drugs I've used. I've never been drawn towards opiates but I've dabbled with oxy (few times) and tramadol (fair bit) but their not for me fortunately.
On the other hand at first I found Kratom to be the perfect drug for every occasion. Going to the pub/restaurant, on a comedown, feeling ill, tired from working, feeling stressed? - Kratom seemed to be the perfect accompaniment.
I realised early on that you need to find the right dosage and if you go over it you will feel very ill.
I used it on and off in the UK but when I moved to Netherlands I fell into using most days and usually combining with a couple of beers. Because of the nature of how I was using it (and probably others can relate) I wasn't concerned with my habit. There was no hangover, no nodding out or missing work and I purchased it from a local hippy Dutch shop very cheap and civilised

. I felt healthier as I was drinking less booze as the kratom gave me a buzz from 2 beers.
I now know that kratom is quite a complex creature and was also providing a mild SSRI type effect, which wasn't something I signed up for. I noticed If I used fairly large doses of kratom then my interest in sex dropped significantly. This seems to be a common side effect and not one I can accept.
In the end I left the Netherlands and quit kratom. The withdrawals were nasty. brain zaps, sleep paralysis, sickness, insomnia, anxiety. Childs play compared to what I've heard strong opiates withdrawals are like but bad enough to stop me from ever taking kratom again.
Saying all this, it did feel like a relatively benign substance. And I hear great things about its use for pain management and withdrawals from heavy opiates. I would pick it over tramadol for moderate pain management.