I've been taking kratom daily since 2014. At the maximum, I took 60g/day in 3 doses of 20g. This was a bit outrageous... I do know that it certainly is high quality product. I have quite a lot of opioid experience and did so prior to beginning kratom use.
I'm now stable at ~30g/day. 10g upon waking, 7.5g mid day, and then 15g in the evening with my diazepam for relaxation. I mainly use reds and always have. I don't recommend anyone start at these doses. I started at about 7g/dose. It took a lot of experimenting and vomiting to find out how to dose that works for me.
Kratom has a nice euphoria that the weaker Rx opioids (hydrocodone etc) don't have. This is likely due to its NE, DA, and various other non-opioidergic actions. I find it hits quicker as well. However, kratom certainly lacks the full mu agonism bliss of stronger/traditional opioids ime.
Dextromethorphan provides a nice potentiation and synergy. Ondansetron is the only reason I've been able to take such high doses. Without ondansetron, anything over 12g and I vomit within 30 minutes. Ondansetron is a lifesaver, even 2mg makes a difference.
As others have said, there's a plethora of information about kratom in these forums. Take some time and search. You'll find all your answers.
Also, kratom will raise your tolerance to opioids. It's rather unfortunate...