I use it for 9mm, .40 S&W, and .45 ACP. It is a fast-burning powder that is economical to use if you load a lot of ammunition. It is possible to double charge a case in each of these calibers if you're not careful, and the min-max range is narrow, so it is wise to be attentive and cautious when using this powder.
I like it a lot, and find it to be accurate and easy to use. My LEE powder system keeps me within 0.1 gr of what I want, and I never load to max. I went through a few 1 lb cans of it before I started buying the 4lb cans. Might have to step up to 8lbs to keep enough of it around.
For the record, I have used it in .38 special cases, but stopped because it was hard to see the powder in the bottom of the long case in my press. Way too easy to overcharge the case and not notice with .38 special. I use IMR 800X in the .38 special cases now, partially because it fills the case nicely.