I use it all the time. And I shot it in 2f and 3f and never had a problem of any kind with it. Its cost effective, it ignites easy, and has about the same power as Goex. I use their 4f as my priming powder still. The powder as I understand it is made by Schuetzen out of Germany. The same people that make Wano, another powder I shoot. If you don't shoot a lot, spend the extra bucks and get Swiss. That is a wonderful black powder.
Yes, Graf's is not Swiss black powder, but it is not priced like Swiss black powder. In my 30+ years of shooting I have burned off probably 40 pounds or more of just Graf's. I used to burn off about 15 to 20 pounds a year. And friends and I shot it for many years straight. Right now I am on a Schuetzen powder kick because I found it on sale and purchased a case. Since it shot like Graf's powder I figured to save a couple bucks.
Those that dislike Graf's black powder I am sure have their reasons. But having shot most every kind of powder in cap and flintlocks, on the market... I would take Graf's any day.
One powder I avoid like the plague is called Elephant Black Powder. That stuff was so bad, I made a powder trail with it (like in Daniel Boone movies) and torched it just to see it burn. Another powder that was all right but ..... is called KIK. Its pretty reasonable in the price range. I shot a lot of that. About 15 pounds of it. I also shot a lot of Wano. Wano was a good powder to shoot. One powder I want to try next is made by Goex called Old Eynsford. I hear that is a good powder.
I get my powder at Powder Inc. Although I admit I have not had to purchase powder in over a year and still have several pounds in the vault.