Wolf ammo used to be "formulated" different in that it had a lacquer coating. This lacquer coating would sometimes cause build-up in the chambers of some guns, thus causing feeding/extraction problems, leading to a poor reputation for this ammo. This has since been resolved because nearly all of it now comes polymer-coated.
Also, the steel cases are not popular at most shooting ranges, with some places (mostly indoor ranges that sell the brass to reloaders) actually banning the use of any Wolf ammo.
Some people have reported a lot of carbon build-up in chambers that can also cause feeding/extraction problems, and they also say that Wolf ammo is very "dirty" and even smells funny.
You need to keep in mind that all Wolf ammo is loaded according to SAAMI specs, so safety should not be a concern.
I shoot Wolf ammo in my AK, and never have had a problem, although I have never used their handgun ammo.
A general rule-of-thumb that you'll see posted here on THR is:
"Use commie ammunition in commie guns"
This is because you'll see posts now and then about how Wolf ammo won't work in someone's M14, but you'll never, ever, ever, see a post about how Wolf won't work in someone's AK47 or SKS.