I recently started experimenting with Kratom and I find it very pleasant. It has a very similar effect that opiates do. Warm and fuzzy, but still able to function normally. I find that about 5 grams of crushed Bali leaf gets me right. But careful because the bad effects it can cause will sneak up on you! I took 4 grams one afternoon and wasn't feeling enough of a nice buzz after about 90 minutes, so I took another 4 grams. Well, that was the wrong thing to do. About 3 hours had passed since the second dose and I had gone to the grocery shopping to buy things to cook for dinner when out of NOWHERE I started to feel so dizzy I had to grab something to stay standing. I ended up leaving my basket and going home it was so bad. The dizziness was accompanied by mild nausea but after sitting still and quiet for a while the feeling eventually passed. So just beware of this side effect because it comes without ANY warning. Other than that I love this plant and highly recommend trying it.
Also, I have tried a few different strains and they all are a little different.
The best to me so far has been Super green Malaysian. It gave a stimulating yet euphoric feeling with NO side effects.