For the Buu saga and for what I saw of it (up until Buu's resurrection at the beginning), it doesn't have any added value : it skips the stuff that wasn't in the manga, but it doesn't actually speed up the stuff that was in it but was super slow.
So basically, it's still super slow, and there isn't any visual improvement either. The very beginning during the Raditz fight up to maybe the Namek saga, there were visual improvements, but quickly less and less ; in the Cell saga, there was almost no difference.
In short, the original anime wasn't very good, and the Kai version has no added value, so it's still not very good.
If I struggled to the end of my determination, to the end of my way of life with my followers, if the result is ruin, then this ruin is inevitable. Grieve. Shed tears. But you cannot regret.